21636604020 has 24 divisors (see below), whose sum is σ = 60582491424. Its totient is φ = 5769761056.

The previous prime is 21636604013. The next prime is 21636604049. The reversal of 21636604020 is 2040663612.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 180304974 + ... + 180305093.

It is an arithmetic number, because the mean of its divisors is an integer number (2524270476).

Almost surely, 2^21636604020 is an apocalyptic number.

21636604020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21636604020 is an abundant number, since it is smaller than the sum of its proper divisors (38945887404).

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

21636604020 is a wasteful number, since it uses less digits than its factorization.

21636604020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 360610079 (or 360610077 counting only the distinct ones).

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

The spelling of 21636604020 in words is "twenty-one billion, six hundred thirty-six million, six hundred four thousand, twenty".