21369761856 has 63 divisors (see below), whose sum is σ = 61262621823. Its totient is φ = 7122084480.

The previous prime is 21369761839. The next prime is 21369761869. The reversal of 21369761856 is 65816796312.

The square root of 21369761856 is 146184.

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

21369761856 is a `hidden beast` number, since 2 + 13 + 6 + 9 + 7 + 618 + 5 + 6 = 666.

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, 3505371 + ... + 3511461.

Almost surely, 2^21369761856 is an apocalyptic number.

21369761856 is the 146184-th square number.

It is an amenable number.

21369761856 is an abundant number, since it is smaller than the sum of its proper divisors (39892859967).

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

21369761856 is an frugal number, since it uses more digits than its factorization.

21369761856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12200 (or 6096 counting only the distinct ones).

The product of its digits is 3265920, while the sum is 54.

It can be divided in two parts, 21369 and 761856, that added together give a square (783225 = 885²).

The spelling of 21369761856 in words is "twenty-one billion, three hundred sixty-nine million, seven hundred sixty-one thousand, eight hundred fifty-six".