21632730 has 64 divisors (see below), whose sum is σ = 61267968. Its totient is φ = 4783680.

The previous prime is 21632717. The next prime is 21632731. The reversal of 21632730 is 3723612.

It is a self number, because there is not a number n which added to its sum of digits gives 21632730.

It is not an unprimeable number, because it can be changed into a prime (21632731) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 4849 + ... + 8171.

It is an arithmetic number, because the mean of its divisors is an integer number (957312).

Almost surely, 2^21632730 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21632730, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30633984).

21632730 is an abundant number, since it is smaller than the sum of its proper divisors (39635238).

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

21632730 is a wasteful number, since it uses less digits than its factorization.

21632730 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3371.

The product of its (nonzero) digits is 1512, while the sum is 24.

The square root of 21632730 is about 4651.0998699232. The cubic root of 21632730 is about 278.6359249555.

The spelling of 21632730 in words is "twenty-one million, six hundred thirty-two thousand, seven hundred thirty".