21132221 has 12 divisors (see below), whose sum is σ = 23624640. Its totient is φ = 18746280.

The previous prime is 21132211. The next prime is 21132229. The reversal of 21132221 is 12223112.

It is a happy number.

It is not a de Polignac number, because 21132221 - 2¹⁴ = 21115837 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21132196 and 21132205.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21132229) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 19820 + ... + 20858.

It is an arithmetic number, because the mean of its divisors is an integer number (1968720).

Almost surely, 2^21132221 is an apocalyptic number.

It is an amenable number.

21132221 is a deficient number, since it is larger than the sum of its proper divisors (2492419).

21132221 is a wasteful number, since it uses less digits than its factorization.

21132221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1136 (or 1093 counting only the distinct ones).

The product of its digits is 48, while the sum is 14.

The square root of 21132221 is about 4596.9795518362. The cubic root of 21132221 is about 276.4702347549.

Adding to 21132221 its reverse (12223112), we get a palindrome (33355333).

It can be divided in two parts, 2113 and 2221, that added together give a palindrome (4334).

The spelling of 21132221 in words is "twenty-one million, one hundred thirty-two thousand, two hundred twenty-one".