21404725 has 24 divisors (see below), whose sum is σ = 27855360. Its totient is φ = 16296000.

The previous prime is 21404689. The next prime is 21404729. The reversal of 21404725 is 52740412.

It is not a de Polignac number, because 21404725 - 2⁷ = 21404597 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (25).

It is a self number, because there is not a number n which added to its sum of digits gives 21404725.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21404729) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 54831 + ... + 55219.

It is an arithmetic number, because the mean of its divisors is an integer number (1160640).

Almost surely, 2^21404725 is an apocalyptic number.

21404725 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21404725 is a deficient number, since it is larger than the sum of its proper divisors (6450635).

21404725 is a wasteful number, since it uses less digits than its factorization.

21404725 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 501 (or 496 counting only the distinct ones).

The product of its (nonzero) digits is 2240, while the sum is 25.

The square root of 21404725 is about 4626.5240732109. The cubic root of 21404725 is about 277.6535416288.

The spelling of 21404725 in words is "twenty-one million, four hundred four thousand, seven hundred twenty-five".