129072321 has 27 divisors (see below), whose sum is σ = 217278243. Its totient is φ = 73619280.

The previous prime is 129072319. The next prime is 129072323. The reversal of 129072321 is 123270921.

The square root of 129072321 is 11361.

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

It is an interprime number because it is at equal distance from previous prime (129072319) and next prime (129072323).

It can be written as a sum of positive squares in only one way, i.e., 51279921 + 77792400 = 7161^2 + 8820^2 .

It is not a de Polignac number, because 129072321 - 2¹ = 129072319 is a prime.

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

It is not an unprimeable number, because it can be changed into a prime (129072323) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 238311 + ... + 238851.

Almost surely, 2^129072321 is an apocalyptic number.

129072321 is the 11361-st square number.

129072321 is the 5681-st centered octagonal number.

It is an amenable number.

129072321 is a deficient number, since it is larger than the sum of its proper divisors (88205922).

129072321 is an frugal number, since it uses more digits than its factorization.

129072321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1102 (or 551 counting only the distinct ones).

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

The cubic root of 129072321 is about 505.3718412910.

The spelling of 129072321 in words is "one hundred twenty-nine million, seventy-two thousand, three hundred twenty-one".