21490680931 has 4 divisors (see below), whose sum is σ = 21515020072. Its totient is φ = 21466341792.

The previous prime is 21490680929. The next prime is 21490680941. The reversal of 21490680931 is 13908609412.

It is a happy number.

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 21490680931 - 2¹ = 21490680929 is a prime.

It is a super-2 number, since 2×21490680931² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21490680941) 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, 12168246 + ... + 12170011.

It is an arithmetic number, because the mean of its divisors is an integer number (5378755018).

Almost surely, 2^21490680931 is an apocalyptic number.

21490680931 is a deficient number, since it is larger than the sum of its proper divisors (24339141).

21490680931 is an equidigital number, since it uses as much as digits as its factorization.

21490680931 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24339140.

The product of its (nonzero) digits is 93312, while the sum is 43.

The spelling of 21490680931 in words is "twenty-one billion, four hundred ninety million, six hundred eighty thousand, nine hundred thirty-one".