21077813124 has 27 divisors (see below), whose sum is σ = 53282229637. Its totient is φ = 7025647344.

The previous prime is 21077813087. The next prime is 21077813149. The reversal of 21077813124 is 42131877012.

The square root of 21077813124 is 145182.

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

It can be written as a sum of positive squares in only one way, i.e., 4940684100 + 16137129024 = 70290^2 + 127032^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 858994 + ... + 883190.

Almost surely, 2^21077813124 is an apocalyptic number.

21077813124 is the 145182-nd square number.

It is an amenable number.

21077813124 is an abundant number, since it is smaller than the sum of its proper divisors (32204416513).

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

21077813124 is an frugal number, since it uses more digits than its factorization.

21077813124 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 48404 (or 24202 counting only the distinct ones).

The product of its (nonzero) digits is 18816, while the sum is 36.

Multiplying 21077813124 by its sum of digits (36), we get a square (758801272464 = 871092²).

21077813124 divided by its sum of digits (36) gives a square (585494809 = 24197²).

The spelling of 21077813124 in words is "twenty-one billion, seventy-seven million, eight hundred thirteen thousand, one hundred twenty-four".