21695868 has 72 divisors (see below), whose sum is σ = 56963088. Its totient is φ = 6958848.

The previous prime is 21695837. The next prime is 21695879. The reversal of 21695868 is 86859612.

21695868 is a `hidden beast` number, since 2 + 1 + 69 + 586 + 8 = 666.

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 23 ways as a sum of consecutive naturals, for example, 158296 + ... + 158432.

It is an arithmetic number, because the mean of its divisors is an integer number (791154).

Almost surely, 2^21695868 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21695868, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28481544).

21695868 is an abundant number, since it is smaller than the sum of its proper divisors (35267220).

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

21695868 is a wasteful number, since it uses less digits than its factorization.

21695868 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 283 (or 278 counting only the distinct ones).

The product of its digits is 207360, while the sum is 45.

The square root of 21695868 is about 4657.8823514554. The cubic root of 21695868 is about 278.9067403259.

The spelling of 21695868 in words is "twenty-one million, six hundred ninety-five thousand, eight hundred sixty-eight".