21855736 has 16 divisors (see below), whose sum is σ = 46833840. Its totient is φ = 9366720.

The previous prime is 21855709. The next prime is 21855737. The reversal of 21855736 is 63755812.

It is a super-2 number, since 2×21855736² = 955346392203392, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21855695 and 21855704.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21855737) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 195085 + ... + 195196.

It is an arithmetic number, because the mean of its divisors is an integer number (2927115).

Almost surely, 2^21855736 is an apocalyptic number.

It is an amenable number.

21855736 is an abundant number, since it is smaller than the sum of its proper divisors (24978104).

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

21855736 is a wasteful number, since it uses less digits than its factorization.

21855736 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 390294 (or 390290 counting only the distinct ones).

The product of its digits is 50400, while the sum is 37.

The square root of 21855736 is about 4675.0118716427. The cubic root of 21855736 is about 279.5901145568.

It can be divided in two parts, 2185 and 5736, that added together give a square (7921 = 89²).

The spelling of 21855736 in words is "twenty-one million, eight hundred fifty-five thousand, seven hundred thirty-six".