21458020 has 12 divisors (see below), whose sum is σ = 45061884. Its totient is φ = 8583200.

The previous prime is 21458009. The next prime is 21458027. The reversal of 21458020 is 2085412.

It can be written as a sum of positive squares in 2 ways, for example, as 4218916 + 17239104 = 2054^2 + 4152^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21457982 and 21458000.

It is not an unprimeable number, because it can be changed into a prime (21458027) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 536431 + ... + 536470.

It is an arithmetic number, because the mean of its divisors is an integer number (3755157).

Almost surely, 2^21458020 is an apocalyptic number.

21458020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21458020 is an abundant number, since it is smaller than the sum of its proper divisors (23603864).

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

21458020 is a wasteful number, since it uses less digits than its factorization.

21458020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1072910 (or 1072908 counting only the distinct ones).

The product of its (nonzero) digits is 640, while the sum is 22.

The square root of 21458020 is about 4632.2802160491. The cubic root of 21458020 is about 277.8837911203.

The spelling of 21458020 in words is "twenty-one million, four hundred fifty-eight thousand, twenty".