21615488 has 32 divisors (see below), whose sum is σ = 43990560. Its totient is φ = 10574848.

The previous prime is 21615481. The next prime is 21615493. The reversal of 21615488 is 88451612.

It is a tau number, because it is divible by the number of its divisors (32).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21615481) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4220 + ... + 7812.

It is an arithmetic number, because the mean of its divisors is an integer number (1374705).

Almost surely, 2^21615488 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 21615488, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21995280).

21615488 is an abundant number, since it is smaller than the sum of its proper divisors (22375072).

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

21615488 is an equidigital number, since it uses as much as digits as its factorization.

21615488 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3654 (or 3642 counting only the distinct ones).

The product of its digits is 15360, while the sum is 35.

The square root of 21615488 is about 4649.2459603682. The cubic root of 21615488 is about 278.5618779356.

The spelling of 21615488 in words is "twenty-one million, six hundred fifteen thousand, four hundred eighty-eight".