251631120557 has 16 divisors (see below), whose sum is σ = 271012230000. Its totient is φ = 232764887040.

The previous prime is 251631120541. The next prime is 251631120577. The reversal of 251631120557 is 755021136152.

It can be written as a sum of positive squares in 8 ways, for example, as 27200585476 + 224430535081 = 164926^2 + 473741^2 .

It is a cyclic number.

It is not a de Polignac number, because 251631120557 - 2⁴ = 251631120541 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 251631120557.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (251631120527) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1242569 + ... + 1430817.

It is an arithmetic number, because the mean of its divisors is an integer number (16938264375).

Almost surely, 2^251631120557 is an apocalyptic number.

It is an amenable number.

251631120557 is a deficient number, since it is larger than the sum of its proper divisors (19381109443).

251631120557 is a wasteful number, since it uses less digits than its factorization.

251631120557 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 189616.

The product of its (nonzero) digits is 63000, while the sum is 38.

The spelling of 251631120557 in words is "two hundred fifty-one billion, six hundred thirty-one million, one hundred twenty thousand, five hundred fifty-seven".