1951878361 has 4 divisors (see below), whose sum is σ = 1951989300. Its totient is φ = 1951767424.

The previous prime is 1951878343. The next prime is 1951878391. The reversal of 1951878361 is 1638781591.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 1638781591 = 2417 ⋅678023.

It can be written as a sum of positive squares in 2 ways, for example, as 1674855625 + 277022736 = 40925^2 + 16644^2 .

It is a cyclic number.

It is not a de Polignac number, because 1951878361 - 2¹⁷ = 1951747289 is a prime.

It is a super-2 number, since 2×1951878361² = 7619658272280092642, which contains 22 as substring.

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1951878301) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 22576 + ... + 66433.

It is an arithmetic number, because the mean of its divisors is an integer number (487997325).

Almost surely, 2^1951878361 is an apocalyptic number.

It is an amenable number.

1951878361 is a deficient number, since it is larger than the sum of its proper divisors (110939).

1951878361 is an equidigital number, since it uses as much as digits as its factorization.

1951878361 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 110938.

The product of its digits is 362880, while the sum is 49.

The square root of 1951878361 is about 44180.0674626013. The cubic root of 1951878361 is about 1249.7339937432.

It can be divided in two parts, 19518 and 78361, that added together give a palindrome (97879).

The spelling of 1951878361 in words is "one billion, nine hundred fifty-one million, eight hundred seventy-eight thousand, three hundred sixty-one".