636778464256 has 99 divisors (see below), whose sum is σ = 1399794034807. Its totient is φ = 289317079040.

The previous prime is 636778464221. The next prime is 636778464277. The reversal of 636778464256 is 652464877636.

It is a happy number.

The square root of 636778464256 is 797984.

It is a perfect power (a square), and thus also a powerful number.

It is a Harshad number since it is a multiple of its sum of digits (64).

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 280889235 + ... + 280891501.

Almost surely, 2^636778464256 is an apocalyptic number.

636778464256 is the 797984-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 636778464256

636778464256 is an abundant number, since it is smaller than the sum of its proper divisors (763015570551).

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

636778464256 is an frugal number, since it uses more digits than its factorization.

636778464256 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4576 (or 2280 counting only the distinct ones).

The product of its digits is 243855360, while the sum is 64.

Multiplying 636778464256 by its sum of digits (64), we get a square (40753821712384 = 6383872²).

636778464256 divided by its sum of digits (64) gives a square (9949663504 = 99748²).

The spelling of 636778464256 in words is "six hundred thirty-six billion, seven hundred seventy-eight million, four hundred sixty-four thousand, two hundred fifty-six".