21885685 has 16 divisors (see below), whose sum is σ = 27132912. Its totient is φ = 16934400.

The previous prime is 21885671. The next prime is 21885697. The reversal of 21885685 is 58658812.

21885685 = 34² + 35² + ... + 403².

It can be written as a sum of positive squares in 8 ways, for example, as 272484 + 21613201 = 522^2 + 4649^2 .

It is not a de Polignac number, because 21885685 - 2⁵ = 21885653 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 51775 + ... + 52195.

It is an arithmetic number, because the mean of its divisors is an integer number (1695807).

Almost surely, 2^21885685 is an apocalyptic number.

It is an amenable number.

21885685 is a deficient number, since it is larger than the sum of its proper divisors (5247227).

21885685 is a wasteful number, since it uses less digits than its factorization.

21885685 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 744.

The product of its digits is 153600, while the sum is 43.

The square root of 21885685 is about 4678.2138685614. The cubic root of 21885685 is about 279.7177640753.

The spelling of 21885685 in words is "twenty-one million, eight hundred eighty-five thousand, six hundred eighty-five".