21573734400 has 819 divisors, whose sum is σ = 85203445471. Its totient is φ = 5414584320.

The previous prime is 21573734389. The next prime is 21573734459. The reversal of 21573734400 is 443737512.

The square root of 21573734400 is 146880.

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

21573734400 is a `hidden beast` number, since 215 + 7 + 3 + 7 + 34 + 400 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 504631296 + 21069103104 = 22464^2 + 145152^2 .

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

It is a Duffinian number.

It is a nialpdrome in base 12.

It is an unprimeable number.

It is a polite number, since it can be written in 62 ways as a sum of consecutive naturals, for example, 1269043192 + ... + 1269043208.

Almost surely, 2^21573734400 is an apocalyptic number.

21573734400 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

21573734400 is the 146880-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21573734400

21573734400 is an abundant number, since it is smaller than the sum of its proper divisors (63629711071).

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

21573734400 is an frugal number, since it uses more digits than its factorization.

21573734400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 86 (or 27 counting only the distinct ones).

The product of its (nonzero) digits is 70560, while the sum is 36.

Multiplying 21573734400 by its sum of digits (36), we get a square (776654438400 = 881280²).

21573734400 divided by its sum of digits (36) gives a square (599270400 = 24480²).

The spelling of 21573734400 in words is "twenty-one billion, five hundred seventy-three million, seven hundred thirty-four thousand, four hundred".