21887808 has 56 divisors (see below), whose sum is σ = 59923680. Its totient is φ = 7042560.

The previous prime is 21887807. The next prime is 21887821. The reversal of 21887808 is 80878812.

It is a happy number.

It is a super-2 number, since 2×21887808² = 958152278089728, which contains 22 as substring.

It is a Smith number, since the sum of its digits (42) coincides with the sum of the digits of its prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 21887808.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21887807) 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, 3603 + ... + 7533.

Almost surely, 2^21887808 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21887808, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29961840).

21887808 is an abundant number, since it is smaller than the sum of its proper divisors (38035872).

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

21887808 is a wasteful number, since it uses less digits than its factorization.

21887808 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3975 (or 3965 counting only the distinct ones).

The product of its (nonzero) digits is 57344, while the sum is 42.

The square root of 21887808 is about 4678.4407658963. The cubic root of 21887808 is about 279.7268083678.

The spelling of 21887808 in words is "twenty-one million, eight hundred eighty-seven thousand, eight hundred eight".