21929725 has 12 divisors (see below), whose sum is σ = 27410944. Its totient is φ = 17403120.

The previous prime is 21929723. The next prime is 21929749. The reversal of 21929725 is 52792912.

It is not a de Polignac number, because 21929725 - 2¹ = 21929723 is a prime.

It is a hoax number, since the sum of its digits (37) coincides with the sum of the digits of its distinct prime factors.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21929723) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 279 + ... + 6628.

Almost surely, 2^21929725 is an apocalyptic number.

21929725 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21929725 is a deficient number, since it is larger than the sum of its proper divisors (5481219).

21929725 is a wasteful number, since it uses less digits than its factorization.

21929725 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7044 (or 7039 counting only the distinct ones).

The product of its digits is 22680, while the sum is 37.

The square root of 21929725 is about 4682.9184276474. The cubic root of 21929725 is about 279.9052613159.

The spelling of 21929725 in words is "twenty-one million, nine hundred twenty-nine thousand, seven hundred twenty-five".