21155132 has 24 divisors (see below), whose sum is σ = 39219600. Its totient is φ = 9956736.

The previous prime is 21155131. The next prime is 21155149. The reversal of 21155132 is 23155112.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21155131) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12344 + ... + 13952.

It is an arithmetic number, because the mean of its divisors is an integer number (1634150).

Almost surely, 2^21155132 is an apocalyptic number.

It is an amenable number.

21155132 is a deficient number, since it is larger than the sum of its proper divisors (18064468).

21155132 is a wasteful number, since it uses less digits than its factorization.

21155132 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1805 (or 1803 counting only the distinct ones).

The product of its digits is 300, while the sum is 20.

The square root of 21155132 is about 4599.4708391292. The cubic root of 21155132 is about 276.5701125954.

Subtracting from 21155132 its sum of digits (20), we obtain a palindrome (21155112).

The spelling of 21155132 in words is "twenty-one million, one hundred fifty-five thousand, one hundred thirty-two".