129721289 has 2 divisors, whose sum is σ = 129721290. Its totient is φ = 129721288.

The previous prime is 129721243. The next prime is 129721307. The reversal of 129721289 is 982127921.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 71961289 + 57760000 = 8483^2 + 7600^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-129721289 is a prime.

It is a super-2 number, since 2×129721289² = 33655225639643042, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (129721489) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64860644 + 64860645.

It is an arithmetic number, because the mean of its divisors is an integer number (64860645).

Almost surely, 2^129721289 is an apocalyptic number.

It is an amenable number.

129721289 is a deficient number, since it is larger than the sum of its proper divisors (1).

129721289 is an equidigital number, since it uses as much as digits as its factorization.

129721289 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 36288, while the sum is 41.

The square root of 129721289 is about 11389.5254071449. The cubic root of 129721289 is about 506.2174189467.

The spelling of 129721289 in words is "one hundred twenty-nine million, seven hundred twenty-one thousand, two hundred eighty-nine".