21132729 has 6 divisors (see below), whose sum is σ = 30525066. Its totient is φ = 14088480.

The previous prime is 21132721. The next prime is 21132733. The reversal of 21132729 is 92723112.

It can be written as a sum of positive squares in only one way, i.e., 15586704 + 5546025 = 3948^2 + 2355^2 .

It is not a de Polignac number, because 21132729 - 2³ = 21132721 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21132721) 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, 1174032 + ... + 1174049.

It is an arithmetic number, because the mean of its divisors is an integer number (5087511).

Almost surely, 2^21132729 is an apocalyptic number.

It is an amenable number.

21132729 is a deficient number, since it is larger than the sum of its proper divisors (9392337).

21132729 is a wasteful number, since it uses less digits than its factorization.

21132729 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2348087 (or 2348084 counting only the distinct ones).

The product of its digits is 1512, while the sum is 27.

The square root of 21132729 is about 4597.0348051760. The cubic root of 21132729 is about 276.4724501042.

The spelling of 21132729 in words is "twenty-one million, one hundred thirty-two thousand, seven hundred twenty-nine".