21683851 has 16 divisors (see below), whose sum is σ = 25804800. Its totient is φ = 17827488.

The previous prime is 21683843. The next prime is 21683899. The reversal of 21683851 is 15838612.

It is not a de Polignac number, because 21683851 - 2³ = 21683843 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21683801) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 45030 + ... + 45508.

It is an arithmetic number, because the mean of its divisors is an integer number (1612800).

Almost surely, 2^21683851 is an apocalyptic number.

21683851 is a deficient number, since it is larger than the sum of its proper divisors (4120949).

21683851 is a wasteful number, since it uses less digits than its factorization.

21683851 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 738.

The product of its digits is 11520, while the sum is 34.

The square root of 21683851 is about 4656.5922089013. The cubic root of 21683851 is about 278.8552367970.

The spelling of 21683851 in words is "twenty-one million, six hundred eighty-three thousand, eight hundred fifty-one".