251021240405491 has 2 divisors, whose sum is σ = 251021240405492. Its totient is φ = 251021240405490.

The previous prime is 251021240405329. The next prime is 251021240405581. The reversal of 251021240405491 is 194504042120152.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 251021240405491 - 2⁴³ = 242225147383283 is a prime.

It is a super-2 number, since 2×251021240405491² (a number of 30 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (251021240405291) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 125510620202745 + 125510620202746.

It is an arithmetic number, because the mean of its divisors is an integer number (125510620202746).

Almost surely, 2^{251021240405491} is an apocalyptic number.

251021240405491 is a deficient number, since it is larger than the sum of its proper divisors (1).

251021240405491 is an equidigital number, since it uses as much as digits as its factorization.

251021240405491 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 115200, while the sum is 40.

The spelling of 251021240405491 in words is "two hundred fifty-one trillion, twenty-one billion, two hundred forty million, four hundred five thousand, four hundred ninety-one".