21766725 has 36 divisors (see below), whose sum is σ = 40441856. Its totient is φ = 11605680.

The previous prime is 21766721. The next prime is 21766739. The reversal of 21766725 is 52766712.

It is not a de Polignac number, because 21766725 - 2² = 21766721 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21766725.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21766721) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 4284 + ... + 7866.

Almost surely, 2^21766725 is an apocalyptic number.

21766725 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21766725 is a deficient number, since it is larger than the sum of its proper divisors (18675131).

21766725 is an equidigital number, since it uses as much as digits as its factorization.

21766725 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3608 (or 3591 counting only the distinct ones).

The product of its digits is 35280, while the sum is 36.

The square root of 21766725 is about 4665.4822901818. The cubic root of 21766725 is about 279.2100395470.

The spelling of 21766725 in words is "twenty-one million, seven hundred sixty-six thousand, seven hundred twenty-five".