21310243961 has 2 divisors, whose sum is σ = 21310243962. Its totient is φ = 21310243960.

The previous prime is 21310243883. The next prime is 21310244047. The reversal of 21310243961 is 16934201312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17009376400 + 4300867561 = 130420^2 + 65581^2 .

It is a cyclic number.

It is not a de Polignac number, because 21310243961 - 2²⁶ = 21243135097 is a prime.

It is not a weakly prime, because it can be changed into another prime (21310245961) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10655121980 + 10655121981.

It is an arithmetic number, because the mean of its divisors is an integer number (10655121981).

Almost surely, 2^21310243961 is an apocalyptic number.

It is an amenable number.

21310243961 is a deficient number, since it is larger than the sum of its proper divisors (1).

21310243961 is an equidigital number, since it uses as much as digits as its factorization.

21310243961 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7776, while the sum is 32.

The spelling of 21310243961 in words is "twenty-one billion, three hundred ten million, two hundred forty-three thousand, nine hundred sixty-one".