21532404 has 48 divisors (see below), whose sum is σ = 54129600. Its totient is φ = 6637056.

The previous prime is 21532403. The next prime is 21532417. The reversal of 21532404 is 40423512.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21532403) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 11142 + ... + 12930.

It is an arithmetic number, because the mean of its divisors is an integer number (1127700).

Almost surely, 2^21532404 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 21532404, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27064800).

21532404 is an abundant number, since it is smaller than the sum of its proper divisors (32597196).

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

21532404 is a wasteful number, since it uses less digits than its factorization.

21532404 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1872 (or 1870 counting only the distinct ones).

The product of its (nonzero) digits is 960, while the sum is 21.

The square root of 21532404 is about 4640.3021453349. The cubic root of 21532404 is about 278.2045145541.

Adding to 21532404 its reverse (40423512), we get a palindrome (61955916).

The spelling of 21532404 in words is "twenty-one million, five hundred thirty-two thousand, four hundred four".