21695638 has 16 divisors (see below), whose sum is σ = 34673184. Its totient is φ = 10145920.

The previous prime is 21695627. The next prime is 21695669. The reversal of 21695638 is 83659612.

It is a self number, because there is not a number n which added to its sum of digits gives 21695638.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3768 + ... + 7588.

It is an arithmetic number, because the mean of its divisors is an integer number (2167074).

Almost surely, 2^21695638 is an apocalyptic number.

21695638 is a deficient number, since it is larger than the sum of its proper divisors (12977546).

21695638 is a wasteful number, since it uses less digits than its factorization.

21695638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4007.

The product of its digits is 77760, while the sum is 40.

The square root of 21695638 is about 4657.8576620588. The cubic root of 21695638 is about 278.9057547499.

The spelling of 21695638 in words is "twenty-one million, six hundred ninety-five thousand, six hundred thirty-eight".