261250542640 has 40 divisors (see below), whose sum is σ = 639376331760. Its totient is φ = 99000205056.

The previous prime is 261250542607. The next prime is 261250542667. The reversal of 261250542640 is 46245052162.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (40).

It is a self number, because there is not a number n which added to its sum of digits gives 261250542640.

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, 85936159 + ... + 85939198.

It is an arithmetic number, because the mean of its divisors is an integer number (15984408294).

Almost surely, 2^261250542640 is an apocalyptic number.

261250542640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

261250542640 is an abundant number, since it is smaller than the sum of its proper divisors (378125789120).

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

261250542640 is a wasteful number, since it uses less digits than its factorization.

261250542640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 171875389 (or 171875383 counting only the distinct ones).

The product of its (nonzero) digits is 115200, while the sum is 37.

The spelling of 261250542640 in words is "two hundred sixty-one billion, two hundred fifty million, five hundred forty-two thousand, six hundred forty".