21256041623 has 2 divisors, whose sum is σ = 21256041624. Its totient is φ = 21256041622.

The previous prime is 21256041601. The next prime is 21256041641. The reversal of 21256041623 is 32614065212.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21256041623 - 2²⁴ = 21239264407 is a prime.

It is a Sophie Germain prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21256041623.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21256041643) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10628020811 + 10628020812.

It is an arithmetic number, because the mean of its divisors is an integer number (10628020812).

Almost surely, 2^21256041623 is an apocalyptic number.

21256041623 is a deficient number, since it is larger than the sum of its proper divisors (1).

21256041623 is an equidigital number, since it uses as much as digits as its factorization.

21256041623 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 17280, while the sum is 32.

The spelling of 21256041623 in words is "twenty-one billion, two hundred fifty-six million, forty-one thousand, six hundred twenty-three".