251642215381 has 2 divisors, whose sum is σ = 251642215382. Its totient is φ = 251642215380.

The previous prime is 251642215361. The next prime is 251642215399. The reversal of 251642215381 is 183512246152.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 234076954225 + 17565261156 = 483815^2 + 132534^2 .

It is a cyclic number.

It is not a de Polignac number, because 251642215381 - 2¹⁵ = 251642182613 is a prime.

It is a super-2 number, since 2×251642215381² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (251642215361) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 125821107690 + 125821107691.

It is an arithmetic number, because the mean of its divisors is an integer number (125821107691).

Almost surely, 2^251642215381 is an apocalyptic number.

It is an amenable number.

251642215381 is a deficient number, since it is larger than the sum of its proper divisors (1).

251642215381 is an equidigital number, since it uses as much as digits as its factorization.

251642215381 is an odious number, because the sum of its binary digits is odd.

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

The spelling of 251642215381 in words is "two hundred fifty-one billion, six hundred forty-two million, two hundred fifteen thousand, three hundred eighty-one".