21489768 has 96 divisors (see below), whose sum is σ = 62604360. Its totient is φ = 6635520.

The previous prime is 21489761. The next prime is 21489791. The reversal of 21489768 is 86798412.

It can be written as a sum of positive squares in 4 ways, for example, as 14424804 + 7064964 = 3798^2 + 2658^2 .

It is not an unprimeable number, because it can be changed into a prime (21489761) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 118638 + ... + 118818.

Almost surely, 2^21489768 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 21489768, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31302180).

21489768 is an abundant number, since it is smaller than the sum of its proper divisors (41114592).

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

21489768 is a wasteful number, since it uses less digits than its factorization.

21489768 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 307 (or 300 counting only the distinct ones).

The product of its digits is 193536, while the sum is 45.

The square root of 21489768 is about 4635.7057715088. The cubic root of 21489768 is about 278.0207703199.

The spelling of 21489768 in words is "twenty-one million, four hundred eighty-nine thousand, seven hundred sixty-eight".