21696725 has 12 divisors (see below), whose sum is σ = 27530976. Its totient is φ = 16952880.

The previous prime is 21696721. The next prime is 21696757. The reversal of 21696725 is 52769612.

It is a happy number.

It is not a de Polignac number, because 21696725 - 2² = 21696721 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21696721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 9017 + ... + 11166.

It is an arithmetic number, because the mean of its divisors is an integer number (2294248).

Almost surely, 2^21696725 is an apocalyptic number.

21696725 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21696725 is a deficient number, since it is larger than the sum of its proper divisors (5834251).

21696725 is a wasteful number, since it uses less digits than its factorization.

21696725 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20236 (or 20231 counting only the distinct ones).

The product of its digits is 45360, while the sum is 38.

The square root of 21696725 is about 4657.9743451419. The cubic root of 21696725 is about 278.9104126062.

The spelling of 21696725 in words is "twenty-one million, six hundred ninety-six thousand, seven hundred twenty-five".