21877818 has 16 divisors (see below), whose sum is σ = 44181696. Its totient is φ = 7221600.

The previous prime is 21877811. The next prime is 21877829. The reversal of 21877818 is 81877812.

It is a super-2 number, since 2×21877818² = 957277840882248, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21877818.

It is not an unprimeable number, because it can be changed into a prime (21877811) 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 7 ways as a sum of consecutive naturals, for example, 17083 + ... + 18318.

It is an arithmetic number, because the mean of its divisors is an integer number (2761356).

Almost surely, 2^21877818 is an apocalyptic number.

21877818 is an abundant number, since it is smaller than the sum of its proper divisors (22303878).

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

21877818 is a wasteful number, since it uses less digits than its factorization.

21877818 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35509.

The product of its digits is 50176, while the sum is 42.

The square root of 21877818 is about 4677.3729806377. The cubic root of 21877818 is about 279.6842443968.

The spelling of 21877818 in words is "twenty-one million, eight hundred seventy-seven thousand, eight hundred eighteen".