21247912031 has 2 divisors, whose sum is σ = 21247912032. Its totient is φ = 21247912030.

The previous prime is 21247911943. The next prime is 21247912061. The reversal of 21247912031 is 13021974212.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21247912031 is a prime.

It is a super-2 number, since 2×21247912031² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21247912061) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10623956015 + 10623956016.

It is an arithmetic number, because the mean of its divisors is an integer number (10623956016).

Almost surely, 2^21247912031 is an apocalyptic number.

21247912031 is a deficient number, since it is larger than the sum of its proper divisors (1).

21247912031 is an equidigital number, since it uses as much as digits as its factorization.

21247912031 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6048, while the sum is 32.

The spelling of 21247912031 in words is "twenty-one billion, two hundred forty-seven million, nine hundred twelve thousand, thirty-one".