21638070 has 32 divisors (see below), whose sum is σ = 57702240. Its totient is φ = 5770080.

The previous prime is 21638069. The next prime is 21638117. The reversal of 21638070 is 7083612.

21638070 is a `hidden beast` number, since 21 + 638 + 0 + 7 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 39801 + ... + 40340.

It is an arithmetic number, because the mean of its divisors is an integer number (1803195).

Almost surely, 2^21638070 is an apocalyptic number.

21638070 is an abundant number, since it is smaller than the sum of its proper divisors (36064170).

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

21638070 is a wasteful number, since it uses less digits than its factorization.

21638070 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 80157 (or 80151 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 27.

The square root of 21638070 is about 4651.6738922672. The cubic root of 21638070 is about 278.6588499928.

The spelling of 21638070 in words is "twenty-one million, six hundred thirty-eight thousand, seventy".