21405332 has 12 divisors (see below), whose sum is σ = 40340916. Its totient is φ = 9879360.

The previous prime is 21405313. The next prime is 21405337. The reversal of 21405332 is 23350412.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 4726276 + 16679056 = 2174^2 + 4084^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21405337) 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, 205769 + ... + 205872.

It is an arithmetic number, because the mean of its divisors is an integer number (3361743).

Almost surely, 2^21405332 is an apocalyptic number.

It is an amenable number.

21405332 is a deficient number, since it is larger than the sum of its proper divisors (18935584).

21405332 is a wasteful number, since it uses less digits than its factorization.

21405332 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 411658 (or 411656 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 20.

The square root of 21405332 is about 4626.5896727503. The cubic root of 21405332 is about 277.6561661912.

Adding to 21405332 its reverse (23350412), we get a palindrome (44755744).

The spelling of 21405332 in words is "twenty-one million, four hundred five thousand, three hundred thirty-two".