21353908931 has 2 divisors, whose sum is σ = 21353908932. Its totient is φ = 21353908930.

The previous prime is 21353908859. The next prime is 21353908957. The reversal of 21353908931 is 13980935312.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21353908931 is a prime.

It is a super-2 number, since 2×21353908931² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21353908991) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10676954465 + 10676954466.

It is an arithmetic number, because the mean of its divisors is an integer number (10676954466).

Almost surely, 2^21353908931 is an apocalyptic number.

21353908931 is a deficient number, since it is larger than the sum of its proper divisors (1).

21353908931 is an equidigital number, since it uses as much as digits as its factorization.

21353908931 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 174960, while the sum is 44.

The spelling of 21353908931 in words is "twenty-one billion, three hundred fifty-three million, nine hundred eight thousand, nine hundred thirty-one".