21132971 has 4 divisors (see below), whose sum is σ = 21142200. Its totient is φ = 21123744.

The previous prime is 21132953. The next prime is 21132983. The reversal of 21132971 is 17923112.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21132971 - 2⁶ = 21132907 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 21132971.

It is not an unprimeable number, because it can be changed into a prime (21132931) 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 3 ways as a sum of consecutive naturals, for example, 1715 + ... + 6723.

It is an arithmetic number, because the mean of its divisors is an integer number (5285550).

Almost surely, 2^21132971 is an apocalyptic number.

21132971 is a deficient number, since it is larger than the sum of its proper divisors (9229).

21132971 is an equidigital number, since it uses as much as digits as its factorization.

21132971 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9228.

The product of its digits is 756, while the sum is 26.

The square root of 21132971 is about 4597.0611264154. The cubic root of 21132971 is about 276.4735054353.

The spelling of 21132971 in words is "twenty-one million, one hundred thirty-two thousand, nine hundred seventy-one".