21085850 has 12 divisors (see below), whose sum is σ = 39219774. Its totient is φ = 8434320.

The previous prime is 21085847. The next prime is 21085853. The reversal of 21085850 is 5858012.

It is an interprime number because it is at equal distance from previous prime (21085847) and next prime (21085853).

It can be written as a sum of positive squares in 3 ways, for example, as 15689521 + 5396329 = 3961^2 + 2323^2 .

It is a super-2 number, since 2×21085850² = 889226140445000, which contains 22 as substring.

It is a hoax number, since the sum of its digits (29) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (21085853) 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 5 ways as a sum of consecutive naturals, for example, 210809 + ... + 210908.

Almost surely, 2^21085850 is an apocalyptic number.

21085850 is a deficient number, since it is larger than the sum of its proper divisors (18133924).

21085850 is a wasteful number, since it uses less digits than its factorization.

21085850 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 421729 (or 421724 counting only the distinct ones).

The product of its (nonzero) digits is 3200, while the sum is 29.

The square root of 21085850 is about 4591.9331441126. The cubic root of 21085850 is about 276.2678646405.

The spelling of 21085850 in words is "twenty-one million, eighty-five thousand, eight hundred fifty".