7921017931 has 4 divisors (see below), whose sum is σ = 7924415472. Its totient is φ = 7917620392.

The previous prime is 7921017899. The next prime is 7921017953. The reversal of 7921017931 is 1397101297.

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

It is a cyclic number.

It is not a de Polignac number, because 7921017931 - 2⁵ = 7921017899 is a prime.

It is a super-2 number, since 2×7921017931² (a number of 21 digits) contains 22 as substring.

It is a Smith number, since the sum of its digits (40) 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 (7921017991) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1695271 + ... + 1699936.

It is an arithmetic number, because the mean of its divisors is an integer number (1981103868).

Almost surely, 2^7921017931 is an apocalyptic number.

7921017931 is a deficient number, since it is larger than the sum of its proper divisors (3397541).

7921017931 is a wasteful number, since it uses less digits than its factorization.

7921017931 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3397540.

The product of its (nonzero) digits is 23814, while the sum is 40.

The square root of 7921017931 is about 89000.1007358980. The cubic root of 7921017931 is about 1993.3963810223.

The spelling of 7921017931 in words is "seven billion, nine hundred twenty-one million, seventeen thousand, nine hundred thirty-one".