21457020 has 48 divisors (see below), whose sum is σ = 64703520. Its totient is φ = 5281536.

The previous prime is 21456989. The next prime is 21457021. The reversal of 21457020 is 2075412.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21457021) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 12975 + ... + 14534.

It is an arithmetic number, because the mean of its divisors is an integer number (1347990).

Almost surely, 2^21457020 is an apocalyptic number.

21457020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21457020 is an abundant number, since it is smaller than the sum of its proper divisors (43246500).

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

21457020 is a wasteful number, since it uses less digits than its factorization.

21457020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27534 (or 27532 counting only the distinct ones).

The product of its (nonzero) digits is 560, while the sum is 21.

The square root of 21457020 is about 4632.1722765890. The cubic root of 21457020 is about 277.8794743487.

The spelling of 21457020 in words is "twenty-one million, four hundred fifty-seven thousand, twenty".