1931791681 has 4 divisors (see below), whose sum is σ = 1937359152. Its totient is φ = 1926224212.

The previous prime is 1931791639. The next prime is 1931791699. The reversal of 1931791681 is 1861971391.

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, and also an emirpimes, since its reverse is a distinct semiprime: 1861971391 = 7 ⋅265995913.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1931791681 is a prime.

It is a super-2 number, since 2×1931791681² = 7463638197561611522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1931741681) 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, 2783215 + ... + 2783908.

It is an arithmetic number, because the mean of its divisors is an integer number (484339788).

Almost surely, 2^1931791681 is an apocalyptic number.

It is an amenable number.

1931791681 is a deficient number, since it is larger than the sum of its proper divisors (5567471).

1931791681 is an equidigital number, since it uses as much as digits as its factorization.

1931791681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5567470.

The product of its digits is 81648, while the sum is 46.

The square root of 1931791681 is about 43952.1521771119. The cubic root of 1931791681 is about 1245.4322205914.

The spelling of 1931791681 in words is "one billion, nine hundred thirty-one million, seven hundred ninety-one thousand, six hundred eighty-one".