1809961381 has 4 divisors (see below), whose sum is σ = 1868347264. Its totient is φ = 1751575500.

The previous prime is 1809961357. The next prime is 1809961411. The reversal of 1809961381 is 1831699081.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1809961381 - 2⁹ = 1809960869 is a prime.

It is a super-2 number, since 2×1809961381² = 6551920401422854322, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1809961981) 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, 29192895 + ... + 29192956.

It is an arithmetic number, because the mean of its divisors is an integer number (467086816).

Almost surely, 2^1809961381 is an apocalyptic number.

It is an amenable number.

1809961381 is a deficient number, since it is larger than the sum of its proper divisors (58385883).

1809961381 is an equidigital number, since it uses as much as digits as its factorization.

1809961381 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 58385882.

The product of its (nonzero) digits is 93312, while the sum is 46.

The square root of 1809961381 is about 42543.6408996691. The cubic root of 1809961381 is about 1218.6802401763.

The spelling of 1809961381 in words is "one billion, eight hundred nine million, nine hundred sixty-one thousand, three hundred eighty-one".