21930636 has 144 divisors (see below), whose sum is σ = 67925760. Its totient is φ = 5443200.

The previous prime is 21930619. The next prime is 21930647. The reversal of 21930636 is 63603912.

It is a happy number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 145161 + ... + 145311.

Almost surely, 2^21930636 is an apocalyptic number.

21930636 is a gapful number since it is divisible by the number (26) 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 21930636, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33962880).

21930636 is an abundant number, since it is smaller than the sum of its proper divisors (45995124).

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

21930636 is a wasteful number, since it uses less digits than its factorization.

21930636 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 204 (or 195 counting only the distinct ones).

The product of its (nonzero) digits is 5832, while the sum is 30.

The square root of 21930636 is about 4683.0156950410. The cubic root of 21930636 is about 279.9091371840.

The spelling of 21930636 in words is "twenty-one million, nine hundred thirty thousand, six hundred thirty-six".