72129 has 4 divisors (see below), whose sum is σ = 96176. Its totient is φ = 48084.

The previous prime is 72109. The next prime is 72139. The reversal of 72129 is 92127.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a de Polignac number, because none of the positive numbers 2^k-72129 is a prime.

It is an Ulam number.

It is a D-number.

It is an alternating number because its digits alternate between odd and even.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (72109) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12019 + ... + 12024.

It is an arithmetic number, because the mean of its divisors is an integer number (24044).

2⁷²¹²⁹ is an apocalyptic number.

It is an amenable number.

72129 is a deficient number, since it is larger than the sum of its proper divisors (24047).

72129 is a wasteful number, since it uses less digits than its factorization.

72129 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24046.

The product of its digits is 252, while the sum is 21.

The square root of 72129 is about 268.5684270349. The cubic root of 72129 is about 41.6265070832.

The spelling of 72129 in words is "seventy-two thousand, one hundred twenty-nine".