21732129 has 6 divisors (see below), whose sum is σ = 31390866. Its totient is φ = 14488080.

The previous prime is 21732101. The next prime is 21732131. The reversal of 21732129 is 92123712.

It can be written as a sum of positive squares in only one way, i.e., 21372129 + 360000 = 4623^2 + 600^2 .

It is not a de Polignac number, because 21732129 - 2¹⁹ = 21207841 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21732169) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1207332 + ... + 1207349.

It is an arithmetic number, because the mean of its divisors is an integer number (5231811).

Almost surely, 2^21732129 is an apocalyptic number.

It is an amenable number.

21732129 is a deficient number, since it is larger than the sum of its proper divisors (9658737).

21732129 is a wasteful number, since it uses less digits than its factorization.

21732129 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2414687 (or 2414684 counting only the distinct ones).

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

The square root of 21732129 is about 4661.7731605045. The cubic root of 21732129 is about 279.0620357679.

The spelling of 21732129 in words is "twenty-one million, seven hundred thirty-two thousand, one hundred twenty-nine".