21421625 has 16 divisors (see below), whose sum is σ = 27900288. Its totient is φ = 16390000.

The previous prime is 21421619. The next prime is 21421627. The reversal of 21421625 is 52612412.

It is a happy number.

It is not a de Polignac number, because 21421625 - 2¹⁶ = 21356089 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (23).

It is a self number, because there is not a number n which added to its sum of digits gives 21421625.

It is not an unprimeable number, because it can be changed into a prime (21421627) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 851 + ... + 6600.

It is an arithmetic number, because the mean of its divisors is an integer number (1743768).

Almost surely, 2^21421625 is an apocalyptic number.

21421625 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21421625 is a deficient number, since it is larger than the sum of its proper divisors (6478663).

21421625 is an equidigital number, since it uses as much as digits as its factorization.

21421625 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7489 (or 7479 counting only the distinct ones).

The product of its digits is 960, while the sum is 23.

The square root of 21421625 is about 4628.3501380081. The cubic root of 21421625 is about 277.7265957552.

The spelling of 21421625 in words is "twenty-one million, four hundred twenty-one thousand, six hundred twenty-five".