21312495251 has 2 divisors, whose sum is σ = 21312495252. Its totient is φ = 21312495250.

The previous prime is 21312495223. The next prime is 21312495389. The reversal of 21312495251 is 15259421312.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21312495251 - 2¹⁴ = 21312478867 is a prime.

It is not a weakly prime, because it can be changed into another prime (21312495551) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10656247625 + 10656247626.

It is an arithmetic number, because the mean of its divisors is an integer number (10656247626).

Almost surely, 2^21312495251 is an apocalyptic number.

21312495251 is a deficient number, since it is larger than the sum of its proper divisors (1).

21312495251 is an equidigital number, since it uses as much as digits as its factorization.

21312495251 is an evil number, because the sum of its binary digits is even.

The product of its digits is 21600, while the sum is 35.

The spelling of 21312495251 in words is "twenty-one billion, three hundred twelve million, four hundred ninety-five thousand, two hundred fifty-one".