21642620 has 24 divisors (see below), whose sum is σ = 45623088. Its totient is φ = 8624000.

The previous prime is 21642601. The next prime is 21642637. The reversal of 21642620 is 2624612.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3695 + ... + 7545.

It is an arithmetic number, because the mean of its divisors is an integer number (1900962).

Almost surely, 2^21642620 is an apocalyptic number.

21642620 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21642620 is an abundant number, since it is smaller than the sum of its proper divisors (23980468).

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

21642620 is a wasteful number, since it uses less digits than its factorization.

21642620 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4141 (or 4139 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 23.

The square root of 21642620 is about 4652.1629378172. The cubic root of 21642620 is about 278.6783805225.

The spelling of 21642620 in words is "twenty-one million, six hundred forty-two thousand, six hundred twenty".