21239402971 has 2 divisors, whose sum is σ = 21239402972. Its totient is φ = 21239402970.

The previous prime is 21239402963. The next prime is 21239402981. The reversal of 21239402971 is 17920493212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21239402971 - 2³ = 21239402963 is a prime.

It is a super-2 number, since 2×21239402971² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21239402981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10619701485 + 10619701486.

It is an arithmetic number, because the mean of its divisors is an integer number (10619701486).

Almost surely, 2^21239402971 is an apocalyptic number.

21239402971 is a deficient number, since it is larger than the sum of its proper divisors (1).

21239402971 is an equidigital number, since it uses as much as digits as its factorization.

21239402971 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 54432, while the sum is 40.

The spelling of 21239402971 in words is "twenty-one billion, two hundred thirty-nine million, four hundred two thousand, nine hundred seventy-one".