21237815824 has 15 divisors (see below), whose sum is σ = 41149397613. Its totient is φ = 10618616448.

The previous prime is 21237815821. The next prime is 21237815899. The reversal of 21237815824 is 42851873212.

The square root of 21237815824 is 145732.

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., 18774480400 + 2463335424 = 137020^2 + 49632^2 .

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21237815821) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 564712 + ... + 601144.

Almost surely, 2^21237815824 is an apocalyptic number.

21237815824 is the 145732-nd square number.

It is an amenable number.

21237815824 is a deficient number, since it is larger than the sum of its proper divisors (19911581789).

21237815824 is an frugal number, since it uses more digits than its factorization.

21237815824 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 72874 (or 36435 counting only the distinct ones).

The product of its digits is 215040, while the sum is 43.

The spelling of 21237815824 in words is "twenty-one billion, two hundred thirty-seven million, eight hundred fifteen thousand, eight hundred twenty-four".