21366253584 has 135 divisors (see below), whose sum is σ = 64818512343. Its totient is φ = 6567215616.

The previous prime is 21366253553. The next prime is 21366253589. The reversal of 21366253584 is 48535266312.

The square root of 21366253584 is 146172.

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

21366253584 is a `hidden beast` number, since 2 + 1 + 3 + 6 + 62 + 5 + 3 + 584 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 14025191184 + 7341062400 = 118428^2 + 85680^2 .

It is not an unprimeable number, because it can be changed into a prime (21366253589) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 22802364 + ... + 22803300.

Almost surely, 2^21366253584 is an apocalyptic number.

21366253584 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

21366253584 is the 146172-nd square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21366253584

21366253584 is an abundant number, since it is smaller than the sum of its proper divisors (43452258759).

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

21366253584 is an equidigital number, since it uses as much as digits as its factorization.

21366253584 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1914 (or 955 counting only the distinct ones).

The product of its digits is 1036800, while the sum is 45.

The spelling of 21366253584 in words is "twenty-one billion, three hundred sixty-six million, two hundred fifty-three thousand, five hundred eighty-four".