21453731660 has 48 divisors (see below), whose sum is σ = 46656110592. Its totient is φ = 8277892800.

The previous prime is 21453731657. The next prime is 21453731669. The reversal of 21453731660 is 6613735412.

It is not an unprimeable number, because it can be changed into a prime (21453731669) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 137189 + ... + 248451.

It is an arithmetic number, because the mean of its divisors is an integer number (972002304).

Almost surely, 2^21453731660 is an apocalyptic number.

21453731660 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21453731660, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23328055296).

21453731660 is an abundant number, since it is smaller than the sum of its proper divisors (25202378932).

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

21453731660 is a wasteful number, since it uses less digits than its factorization.

21453731660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 111614 (or 111612 counting only the distinct ones).

The product of its (nonzero) digits is 90720, while the sum is 38.

The spelling of 21453731660 in words is "twenty-one billion, four hundred fifty-three million, seven hundred thirty-one thousand, six hundred sixty".