21908736256 has 135 divisors (see below), whose sum is σ = 49785683983. Its totient is φ = 9615119360.

The previous prime is 21908736253. The next prime is 21908736313. The reversal of 21908736256 is 65263780912.

The square root of 21908736256 is 148016.

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

It can be written as a sum of positive squares in 2 ways, for example, as 52070656 + 21856665600 = 7216^2 + 147840^2 .

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21908736253) by changing a digit.

It is a polite number, since it can be written in 14 ways as a sum of consecutive naturals, for example, 755473650 + ... + 755473678.

Almost surely, 2^21908736256 is an apocalyptic number.

21908736256 is the 148016-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21908736256

21908736256 is an abundant number, since it is smaller than the sum of its proper divisors (27876947727).

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

21908736256 is an frugal number, since it uses more digits than its factorization.

21908736256 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 154 (or 42 counting only the distinct ones).

The product of its (nonzero) digits is 1088640, while the sum is 49.

Multiplying 21908736256 by its sum of digits (49), we get a square (1073528076544 = 1036112²).

The spelling of 21908736256 in words is "twenty-one billion, nine hundred eight million, seven hundred thirty-six thousand, two hundred fifty-six".