21085858 has 8 divisors (see below), whose sum is σ = 33293520. Its totient is φ = 9988020.

The previous prime is 21085853. The next prime is 21085879. The reversal of 21085858 is 85858012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a super-2 number, since 2×21085858² = 889226815192328, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21085853) 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, 277408 + ... + 277483.

It is an arithmetic number, because the mean of its divisors is an integer number (4161690).

Almost surely, 2^21085858 is an apocalyptic number.

21085858 is a deficient number, since it is larger than the sum of its proper divisors (12207662).

21085858 is a wasteful number, since it uses less digits than its factorization.

21085858 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 554912.

The product of its (nonzero) digits is 25600, while the sum is 37.

The square root of 21085858 is about 4591.9340152054. The cubic root of 21085858 is about 276.2678995793.

It can be divided in two parts, 210 and 85858, that added together give a palindrome (86068).

The spelling of 21085858 in words is "twenty-one million, eighty-five thousand, eight hundred fifty-eight".