21851836 has 6 divisors (see below), whose sum is σ = 38240720. Its totient is φ = 10925916.

The previous prime is 21851833. The next prime is 21851839. The reversal of 21851836 is 63815812.

It is an interprime number because it is at equal distance from previous prime (21851833) and next prime (21851839).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21851833) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2731476 + ... + 2731483.

Almost surely, 2^21851836 is an apocalyptic number.

It is an amenable number.

21851836 is a deficient number, since it is larger than the sum of its proper divisors (16388884).

21851836 is a wasteful number, since it uses less digits than its factorization.

21851836 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5462963 (or 5462961 counting only the distinct ones).

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

The square root of 21851836 is about 4674.5947417931. The cubic root of 21851836 is about 279.5734832811.

The spelling of 21851836 in words is "twenty-one million, eight hundred fifty-one thousand, eight hundred thirty-six".