261631865754 has 80 divisors (see below), whose sum is σ = 670124716800. Its totient is φ = 74737943136.

The previous prime is 261631865557. The next prime is 261631865783. The reversal of 261631865754 is 457568136162.

It is a happy number.

261631865754 is a `hidden beast` number, since 2 + 6 + 1 + 63 + 1 + 8 + 6 + 575 + 4 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a self number, because there is not a number n which added to its sum of digits gives 261631865754.

It is an unprimeable number.

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 in 39 ways as a sum of consecutive naturals, for example, 7045167 + ... + 7082205.

It is an arithmetic number, because the mean of its divisors is an integer number (8376558960).

Almost surely, 2^261631865754 is an apocalyptic number.

261631865754 is an abundant number, since it is smaller than the sum of its proper divisors (408492851046).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

261631865754 is a wasteful number, since it uses less digits than its factorization.

261631865754 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43289 (or 43280 counting only the distinct ones).

The product of its digits is 7257600, while the sum is 54.

The spelling of 261631865754 in words is "two hundred sixty-one billion, six hundred thirty-one million, eight hundred sixty-five thousand, seven hundred fifty-four".