21873808 has 40 divisors (see below), whose sum is σ = 47496960. Its totient is φ = 9671040.

The previous prime is 21873779. The next prime is 21873809. The reversal of 21873808 is 80837812.

It is a Harshad number since it is a multiple of its sum of digits (37).

It is not an unprimeable number, because it can be changed into a prime (21873809) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4833 + ... + 8191.

It is an arithmetic number, because the mean of its divisors is an integer number (1187424).

Almost surely, 2^21873808 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 21873808, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23748480).

21873808 is an abundant number, since it is smaller than the sum of its proper divisors (25623152).

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

21873808 is a wasteful number, since it uses less digits than its factorization.

21873808 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3415 (or 3409 counting only the distinct ones).

The product of its (nonzero) digits is 21504, while the sum is 37.

The square root of 21873808 is about 4676.9443015713. The cubic root of 21873808 is about 279.6671555149.

It can be divided in two parts, 2187 and 3808, that added together give a palindrome (5995).

The spelling of 21873808 in words is "twenty-one million, eight hundred seventy-three thousand, eight hundred eight".