21624636 has 72 divisors (see below), whose sum is σ = 56709072. Its totient is φ = 6406400.

The previous prime is 21624601. The next prime is 21624637. The reversal of 21624636 is 63642612.

It is a Smith number, since the sum of its digits (30) coincides with the sum of the digits of its prime factors.

It is a nude number because it is divisible by every one of its digits.

It is a zygodrome in base 11.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21624637) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 76816 + ... + 77096.

It is an arithmetic number, because the mean of its divisors is an integer number (787626).

Almost surely, 2^21624636 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21624636, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28354536).

21624636 is an abundant number, since it is smaller than the sum of its proper divisors (35084436).

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

21624636 is a wasteful number, since it uses less digits than its factorization.

21624636 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 363 (or 350 counting only the distinct ones).

The product of its digits is 10368, while the sum is 30.

The square root of 21624636 is about 4650.2296717474. The cubic root of 21624636 is about 278.6011695869.

The spelling of 21624636 in words is "twenty-one million, six hundred twenty-four thousand, six hundred thirty-six".