21618858 has 16 divisors (see below), whose sum is σ = 43312320. Its totient is φ = 7193856.

The previous prime is 21618847. The next prime is 21618889. The reversal of 21618858 is 85881612.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1098 + ... + 6666.

It is an arithmetic number, because the mean of its divisors is an integer number (2707020).

Almost surely, 2^21618858 is an apocalyptic number.

21618858 is an abundant number, since it is smaller than the sum of its proper divisors (21693462).

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

21618858 is a wasteful number, since it uses less digits than its factorization.

21618858 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6221.

The product of its digits is 30720, while the sum is 39.

The square root of 21618858 is about 4649.6083706050. The cubic root of 21618858 is about 278.5763537403.

The spelling of 21618858 in words is "twenty-one million, six hundred eighteen thousand, eight hundred fifty-eight".