21509155600 has 45 divisors (see below), whose sum is σ = 51682794303. Its totient is φ = 8602488960.

The previous prime is 21509155471. The next prime is 21509155631. The reversal of 21509155600 is 655190512.

The square root of 21509155600 is 146660.

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

It can be written as a sum of positive squares in 4 ways, for example, as 12027070224 + 9482085376 = 109668^2 + 97376^2 .

It is a super-2 number, since 2×21509155600² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

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, 2929534 + ... + 2936866.

Almost surely, 2^21509155600 is an apocalyptic number.

21509155600 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

21509155600 is the 146660-th square number.

It is an amenable number.

21509155600 is an abundant number, since it is smaller than the sum of its proper divisors (30173638703).

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

21509155600 is an frugal number, since it uses more digits than its factorization.

21509155600 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14684 (or 7340 counting only the distinct ones).

The product of its (nonzero) digits is 13500, while the sum is 34.

The spelling of 21509155600 in words is "twenty-one billion, five hundred nine million, one hundred fifty-five thousand, six hundred".