21693868 has 36 divisors (see below), whose sum is σ = 44515632. Its totient is φ = 9223200.

The previous prime is 21693851. The next prime is 21693883. The reversal of 21693868 is 86839612.

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 11 ways as a sum of consecutive naturals, for example, 29230 + ... + 29962.

Almost surely, 2^21693868 is an apocalyptic number.

21693868 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21693868, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22257816).

21693868 is an abundant number, since it is smaller than the sum of its proper divisors (22821764).

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

21693868 is a wasteful number, since it uses less digits than its factorization.

21693868 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 902 (or 893 counting only the distinct ones).

The product of its digits is 124416, while the sum is 43.

The square root of 21693868 is about 4657.6676566711. The cubic root of 21693868 is about 278.8981698672.

It can be divided in two parts, 21 and 693868, that added together give a square (693889 = 833²).

The spelling of 21693868 in words is "twenty-one million, six hundred ninety-three thousand, eight hundred sixty-eight".