21899856 has 160 divisors (see below), whose sum is σ = 67852800. Its totient is φ = 6013440.

The previous prime is 21899831. The next prime is 21899909. The reversal of 21899856 is 65899812.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 371155 + ... + 371213.

It is an arithmetic number, because the mean of its divisors is an integer number (424080).

Almost surely, 2^21899856 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 21899856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33926400).

21899856 is an abundant number, since it is smaller than the sum of its proper divisors (45952944).

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

21899856 is a wasteful number, since it uses less digits than its factorization.

21899856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 137 (or 131 counting only the distinct ones).

The product of its digits is 311040, while the sum is 48.

The square root of 21899856 is about 4679.7281972354. The cubic root of 21899856 is about 279.7781235477.

The spelling of 21899856 in words is "twenty-one million, eight hundred ninety-nine thousand, eight hundred fifty-six".