21685525 has 12 divisors (see below), whose sum is σ = 27024064. Its totient is φ = 17262000.

The previous prime is 21685519. The next prime is 21685549. The reversal of 21685525 is 52558612.

It is not a de Polignac number, because 21685525 - 2¹³ = 21677333 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 11 ways as a sum of consecutive naturals, for example, 3220 + ... + 7330.

Almost surely, 2^21685525 is an apocalyptic number.

21685525 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21685525 is a deficient number, since it is larger than the sum of its proper divisors (5338539).

21685525 is a wasteful number, since it uses less digits than its factorization.

21685525 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4332 (or 4327 counting only the distinct ones).

The product of its digits is 24000, while the sum is 34.

The square root of 21685525 is about 4656.7719506113. The cubic root of 21685525 is about 278.8624125158.

The spelling of 21685525 in words is "twenty-one million, six hundred eighty-five thousand, five hundred twenty-five".