21085356 has 24 divisors (see below), whose sum is σ = 49336560. Its totient is φ = 7008832.

The previous prime is 21085343. The next prime is 21085373. The reversal of 21085356 is 65358012.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2410 + ... + 6926.

It is an arithmetic number, because the mean of its divisors is an integer number (2055690).

Almost surely, 2^21085356 is an apocalyptic number.

It is an amenable number.

21085356 is an abundant number, since it is smaller than the sum of its proper divisors (28251204).

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

21085356 is a wasteful number, since it uses less digits than its factorization.

21085356 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4913 (or 4911 counting only the distinct ones).

The product of its (nonzero) digits is 7200, while the sum is 30.

The square root of 21085356 is about 4591.8793538158. The cubic root of 21085356 is about 276.2657071527.

It can be divided in two parts, 2 and 1085356, that multiplied together give a palindrome (2170712).

The spelling of 21085356 in words is "twenty-one million, eighty-five thousand, three hundred fifty-six".