21255890436 has 135 divisors (see below), whose sum is σ = 60342665383. Its totient is φ = 6304132560.

The previous prime is 21255890399. The next prime is 21255890441. The reversal of 21255890436 is 63409855212.

The square root of 21255890436 is 145794.

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

21255890436 is a `hidden beast` number, since 2 + 1 + 2 + 558 + 90 + 4 + 3 + 6 = 666.

It is a junction number, because it is equal to n+sod(n) for n = 21255890391 and 21255890400.

It is an unprimeable number.

It is a polite number, since it can be written in 44 ways as a sum of consecutive naturals, for example, 452252965 + ... + 452253011.

Almost surely, 2^21255890436 is an apocalyptic number.

21255890436 is the 145794-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21255890436

21255890436 is an abundant number, since it is smaller than the sum of its proper divisors (39086774947).

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

21255890436 is an frugal number, since it uses more digits than its factorization.

21255890436 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 220 (or 63 counting only the distinct ones).

The product of its (nonzero) digits is 518400, while the sum is 45.

The spelling of 21255890436 in words is "twenty-one billion, two hundred fifty-five million, eight hundred ninety thousand, four hundred thirty-six".