21851704 has 16 divisors (see below), whose sum is σ = 46825200. Its totient is φ = 9364992.

The previous prime is 21851689. The next prime is 21851707. The reversal of 21851704 is 40715812.

It is a Harshad number since it is a multiple of its sum of digits (28).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21851707) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 195049 + ... + 195160.

It is an arithmetic number, because the mean of its divisors is an integer number (2926575).

Almost surely, 2^21851704 is an apocalyptic number.

It is an amenable number.

21851704 is an abundant number, since it is smaller than the sum of its proper divisors (24973496).

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

21851704 is a wasteful number, since it uses less digits than its factorization.

21851704 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 390222 (or 390218 counting only the distinct ones).

The product of its (nonzero) digits is 2240, while the sum is 28.

The square root of 21851704 is about 4674.5806229008. The cubic root of 21851704 is about 279.5729203418.

The spelling of 21851704 in words is "twenty-one million, eight hundred fifty-one thousand, seven hundred four".