1918351861 has 4 divisors (see below), whose sum is σ = 1918558924. Its totient is φ = 1918144800.

The previous prime is 1918351759. The next prime is 1918351933. The reversal of 1918351861 is 1681538191.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 392277636 + 1526074225 = 19806^2 + 39065^2 .

It is a cyclic number.

It is not a de Polignac number, because 1918351861 - 2¹⁵ = 1918319093 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1918451861) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 88950 + ... + 108391.

It is an arithmetic number, because the mean of its divisors is an integer number (479639731).

Almost surely, 2^1918351861 is an apocalyptic number.

It is an amenable number.

1918351861 is a deficient number, since it is larger than the sum of its proper divisors (207063).

1918351861 is an equidigital number, since it uses as much as digits as its factorization.

1918351861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 207062.

The product of its digits is 51840, while the sum is 43.

The square root of 1918351861 is about 43798.9938354753. The cubic root of 1918351861 is about 1242.5372650818.

The spelling of 1918351861 in words is "one billion, nine hundred eighteen million, three hundred fifty-one thousand, eight hundred sixty-one".