21132405 has 48 divisors (see below), whose sum is σ = 42481920. Its totient is φ = 9517824.

The previous prime is 21132383. The next prime is 21132481. The reversal of 21132405 is 50423112.

It is not a de Polignac number, because 21132405 - 2⁶ = 21132341 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 22536 + ... + 23454.

It is an arithmetic number, because the mean of its divisors is an integer number (885040).

Almost surely, 2^21132405 is an apocalyptic number.

It is an amenable number.

21132405 is an abundant number, since it is smaller than the sum of its proper divisors (21349515).

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

21132405 is a wasteful number, since it uses less digits than its factorization.

21132405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1010 (or 1007 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 18.

The square root of 21132405 is about 4596.9995649336. Note that the first 3 decimals coincide. The cubic root of 21132405 is about 276.4710371690.

Adding to 21132405 its reverse (50423112), we get a palindrome (71555517).

The spelling of 21132405 in words is "twenty-one million, one hundred thirty-two thousand, four hundred five".