21729118464 has 243 divisors, whose sum is σ = 65174546073. Its totient is φ = 6962374656.

The previous prime is 21729118457. The next prime is 21729118469. The reversal of 21729118464 is 46481192712.

The square root of 21729118464 is 147408.

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

21729118464 is a `hidden beast` number, since 2 + 1 + 72 + 9 + 118 + 464 = 666.

It can be written as a sum of positive squares in only one way, i.e., 19443513600 + 2285604864 = 139440^2 + 47808^2 .

It is not an unprimeable number, because it can be changed into a prime (21729118469) 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, 261796567 + ... + 261796649.

Almost surely, 2^21729118464 is an apocalyptic number.

21729118464 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

21729118464 is the 147408-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21729118464

21729118464 is an abundant number, since it is smaller than the sum of its proper divisors (43445427609).

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

21729118464 is an frugal number, since it uses more digits than its factorization.

21729118464 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 262 (or 125 counting only the distinct ones).

The product of its digits is 193536, while the sum is 45.

The spelling of 21729118464 in words is "twenty-one billion, seven hundred twenty-nine million, one hundred eighteen thousand, four hundred sixty-four".