21338856 has 128 divisors (see below), whose sum is σ = 73958400. Its totient is φ = 5538240.

The previous prime is 21338851. The next prime is 21338857. The reversal of 21338856 is 65883312.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 21338856.

It is not an unprimeable number, because it can be changed into a prime (21338851) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 15991 + ... + 17273.

It is an arithmetic number, because the mean of its divisors is an integer number (577800).

Almost surely, 2^21338856 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 21338856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36979200).

21338856 is an abundant number, since it is smaller than the sum of its proper divisors (52619544).

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

21338856 is a wasteful number, since it uses less digits than its factorization.

21338856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1316 (or 1306 counting only the distinct ones).

The product of its digits is 34560, while the sum is 36.

The square root of 21338856 is about 4619.3999610339. The cubic root of 21338856 is about 277.3684401954.

It can be divided in two parts, 213388 and 56, that added together give a square (213444 = 462²).

The spelling of 21338856 in words is "twenty-one million, three hundred thirty-eight thousand, eight hundred fifty-six".