21286725 has 24 divisors (see below), whose sum is σ = 36411360. Its totient is φ = 10960320.

The previous prime is 21286717. The next prime is 21286751. The reversal of 21286725 is 52768212.

It is not a de Polignac number, because 21286725 - 2³ = 21286717 is a prime.

It is a super-2 number, since 2×21286725² = 906249322451250, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2719 + ... + 7068.

It is an arithmetic number, because the mean of its divisors is an integer number (1517140).

Almost surely, 2^21286725 is an apocalyptic number.

21286725 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21286725 is a deficient number, since it is larger than the sum of its proper divisors (15124635).

21286725 is a wasteful number, since it uses less digits than its factorization.

21286725 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9829 (or 9824 counting only the distinct ones).

The product of its digits is 13440, while the sum is 33.

The square root of 21286725 is about 4613.7538946069. The cubic root of 21286725 is about 277.1423848865.

The spelling of 21286725 in words is "twenty-one million, two hundred eighty-six thousand, seven hundred twenty-five".