21430639931 has 2 divisors, whose sum is σ = 21430639932. Its totient is φ = 21430639930.

The previous prime is 21430639927. The next prime is 21430640009. The reversal of 21430639931 is 13993603412.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21430639931 - 2² = 21430639927 is a prime.

It is a super-2 number, since 2×21430639931² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21430639921) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10715319965 + 10715319966.

It is an arithmetic number, because the mean of its divisors is an integer number (10715319966).

Almost surely, 2^21430639931 is an apocalyptic number.

21430639931 is a deficient number, since it is larger than the sum of its proper divisors (1).

21430639931 is an equidigital number, since it uses as much as digits as its factorization.

21430639931 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 104976, while the sum is 41.

The spelling of 21430639931 in words is "twenty-one billion, four hundred thirty million, six hundred thirty-nine thousand, nine hundred thirty-one".