21858885 has 12 divisors (see below), whose sum is σ = 37888812. Its totient is φ = 11658048.

The previous prime is 21858857. The next prime is 21858899. The reversal of 21858885 is 58885812.

It can be written as a sum of positive squares in 2 ways, for example, as 15233409 + 6625476 = 3903^2 + 2574^2 .

It is not a de Polignac number, because 21858885 - 2¹¹ = 21856837 is a prime.

It is a super-3 number, since 3×21858885³ (a number of 23 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45), and also a Moran number because the ratio is a prime number: 485753 = 21858885 / (2 + 1 + 8 + 5 + 8 + 8 + 8 + 5).

It is a self number, because there is not a number n which added to its sum of digits gives 21858885.

It is a congruent number.

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 11 ways as a sum of consecutive naturals, for example, 242832 + ... + 242921.

It is an arithmetic number, because the mean of its divisors is an integer number (3157401).

Almost surely, 2^21858885 is an apocalyptic number.

It is an amenable number.

21858885 is a deficient number, since it is larger than the sum of its proper divisors (16029927).

21858885 is a wasteful number, since it uses less digits than its factorization.

21858885 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 485764 (or 485761 counting only the distinct ones).

The product of its digits is 204800, while the sum is 45.

The square root of 21858885 is about 4675.3486501009. The cubic root of 21858885 is about 279.6035418022.

The spelling of 21858885 in words is "twenty-one million, eight hundred fifty-eight thousand, eight hundred eighty-five".