21165606 has 48 divisors (see below), whose sum is σ = 57178368. Its totient is φ = 5497200.

The previous prime is 21165593. The next prime is 21165607. The reversal of 21165606 is 60656112.

It is a happy number.

21165606 is a `hidden beast` number, since 2 + 1 + 1 + 656 + 0 + 6 = 666.

It is a self number, because there is not a number n which added to its sum of digits gives 21165606.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21165607) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 6250 + ... + 9021.

It is an arithmetic number, because the mean of its divisors is an integer number (1191216).

Almost surely, 2^21165606 is an apocalyptic number.

21165606 is an abundant number, since it is smaller than the sum of its proper divisors (36012762).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21165606 is a wasteful number, since it uses less digits than its factorization.

21165606 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15297 (or 15294 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 27.

The square root of 21165606 is about 4600.6093074722. The cubic root of 21165606 is about 276.6157487625.

The spelling of 21165606 in words is "twenty-one million, one hundred sixty-five thousand, six hundred six".