21372129 has 27 divisors (see below), whose sum is σ = 32760273. Its totient is φ = 13425192.

The previous prime is 21372103. The next prime is 21372133. The reversal of 21372129 is 92127312.

The square root of 21372129 is 4623.

It is a perfect power (a square), and thus also a powerful number.

It is not a de Polignac number, because 21372129 - 2¹⁷ = 21241057 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21372149) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 318954 + ... + 319020.

Almost surely, 2^21372129 is an apocalyptic number.

21372129 is the 4623-rd square number.

21372129 is the 2312-nd centered octagonal number.

It is an amenable number.

21372129 is a deficient number, since it is larger than the sum of its proper divisors (11388144).

21372129 is an equidigital number, since it uses as much as digits as its factorization.

21372129 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 186 (or 93 counting only the distinct ones).

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

The cubic root of 21372129 is about 277.5125292614.

The spelling of 21372129 in words is "twenty-one million, three hundred seventy-two thousand, one hundred twenty-nine".