255621809664 has 640 divisors, whose sum is σ = 878202124800. Its totient is φ = 72738570240.

The previous prime is 255621809659. The next prime is 255621809671. The reversal of 255621809664 is 466908126552.

255621809664 is a `hidden beast` number, since 2 + 5 + 5 + 621 + 8 + 0 + 9 + 6 + 6 + 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 255621809664.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 146823834 + ... + 146825574.

It is an arithmetic number, because the mean of its divisors is an integer number (1372190820).

Almost surely, 2^255621809664 is an apocalyptic number.

255621809664 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 255621809664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (439101062400).

255621809664 is an abundant number, since it is smaller than the sum of its proper divisors (622580315136).

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

255621809664 is a wasteful number, since it uses less digits than its factorization.

255621809664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1843 (or 1821 counting only the distinct ones).

The product of its (nonzero) digits is 6220800, while the sum is 54.

The spelling of 255621809664 in words is "two hundred fifty-five billion, six hundred twenty-one million, eight hundred nine thousand, six hundred sixty-four".