251381558421491 has 2 divisors, whose sum is σ = 251381558421492. Its totient is φ = 251381558421490.

The previous prime is 251381558421479. The next prime is 251381558421509. The reversal of 251381558421491 is 194124855183152.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-251381558421491 is a prime.

It is a super-2 number, since 2×251381558421491² (a number of 30 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 251381558421491.

It is not a weakly prime, because it can be changed into another prime (251381558421421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 125690779210745 + 125690779210746.

It is an arithmetic number, because the mean of its divisors is an integer number (125690779210746).

Almost surely, 2^{251381558421491} is an apocalyptic number.

251381558421491 is a deficient number, since it is larger than the sum of its proper divisors (1).

251381558421491 is an equidigital number, since it uses as much as digits as its factorization.

251381558421491 is an evil number, because the sum of its binary digits is even.

The product of its digits is 13824000, while the sum is 59.

The spelling of 251381558421491 in words is "two hundred fifty-one trillion, three hundred eighty-one billion, five hundred fifty-eight million, four hundred twenty-one thousand, four hundred ninety-one".