21275685 has 12 divisors (see below), whose sum is σ = 36877932. Its totient is φ = 11347008.

The previous prime is 21275677. The next prime is 21275693. The reversal of 21275685 is 58657212.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21275677) and next prime (21275693).

It can be written as a sum of positive squares in 2 ways, for example, as 12383361 + 8892324 = 3519^2 + 2982^2 .

It is not a de Polignac number, because 21275685 - 2³ = 21275677 is a prime.

It is a Curzon 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, 236352 + ... + 236441.

It is an arithmetic number, because the mean of its divisors is an integer number (3073161).

Almost surely, 2^21275685 is an apocalyptic number.

It is an amenable number.

21275685 is a deficient number, since it is larger than the sum of its proper divisors (15602247).

21275685 is a wasteful number, since it uses less digits than its factorization.

21275685 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 472804 (or 472801 counting only the distinct ones).

The product of its digits is 33600, while the sum is 36.

The square root of 21275685 is about 4612.5573167171. The cubic root of 21275685 is about 277.0944648639.

The spelling of 21275685 in words is "twenty-one million, two hundred seventy-five thousand, six hundred eighty-five".