21132747 has 6 divisors (see below), whose sum is σ = 30525092. Its totient is φ = 14088492.

The previous prime is 21132739. The next prime is 21132757. The reversal of 21132747 is 74723112.

It is a happy number.

It is not a de Polignac number, because 21132747 - 2³ = 21132739 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21132747.

It is not an unprimeable number, because it can be changed into a prime (21132757) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1174033 + ... + 1174050.

Almost surely, 2^21132747 is an apocalyptic number.

21132747 is a deficient number, since it is larger than the sum of its proper divisors (9392345).

21132747 is a wasteful number, since it uses less digits than its factorization.

21132747 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2348089 (or 2348086 counting only the distinct ones).

The product of its digits is 2352, while the sum is 27.

The square root of 21132747 is about 4597.0367629594. The cubic root of 21132747 is about 276.4725286002.

Adding to 21132747 its reverse (74723112), we get a palindrome (95855859).

The spelling of 21132747 in words is "twenty-one million, one hundred thirty-two thousand, seven hundred forty-seven".