21055020 has 48 divisors (see below), whose sum is σ = 67377408. Its totient is φ = 4812480.

The previous prime is 21055003. The next prime is 21055033. The reversal of 21055020 is 2055012.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 24646 + ... + 25485.

It is an arithmetic number, because the mean of its divisors is an integer number (1403696).

Almost surely, 2^21055020 is an apocalyptic number.

21055020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21055020 is an abundant number, since it is smaller than the sum of its proper divisors (46322388).

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

21055020 is a wasteful number, since it uses less digits than its factorization.

21055020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 50150 (or 50148 counting only the distinct ones).

The product of its (nonzero) digits is 100, while the sum is 15.

The square root of 21055020 is about 4588.5749421798. The cubic root of 21055020 is about 276.1331535624.

The spelling of 21055020 in words is "twenty-one million, fifty-five thousand, twenty".