21365552 has 40 divisors (see below), whose sum is σ = 45361680. Its totient is φ = 9688320.

The previous prime is 21365543. The next prime is 21365569. The reversal of 21365552 is 25556312.

It is a happy number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11402 + ... + 13142.

It is an arithmetic number, because the mean of its divisors is an integer number (1134042).

Almost surely, 2^21365552 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 21365552, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22680840).

21365552 is an abundant number, since it is smaller than the sum of its proper divisors (23996128).

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

21365552 is a wasteful number, since it uses less digits than its factorization.

21365552 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1821 (or 1815 counting only the distinct ones).

The product of its digits is 9000, while the sum is 29.

The square root of 21365552 is about 4622.2886106343. The cubic root of 21365552 is about 277.4840593608.

The spelling of 21365552 in words is "twenty-one million, three hundred sixty-five thousand, five hundred fifty-two".