251603561642 has 16 divisors (see below), whose sum is σ = 397283508960. Its totient is φ = 119176216272.

The previous prime is 251603561609. The next prime is 251603561663. The reversal of 251603561642 is 246165306152.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 251603561642.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1065113 + ... + 1279715.

It is an arithmetic number, because the mean of its divisors is an integer number (24830219310).

Almost surely, 2^251603561642 is an apocalyptic number.

251603561642 is a deficient number, since it is larger than the sum of its proper divisors (145679947318).

251603561642 is a wasteful number, since it uses less digits than its factorization.

251603561642 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 245477.

The product of its (nonzero) digits is 259200, while the sum is 41.

Adding to 251603561642 its reverse (246165306152), we get a palindrome (497768867794).

The spelling of 251603561642 in words is "two hundred fifty-one billion, six hundred three million, five hundred sixty-one thousand, six hundred forty-two".