129721317 has 12 divisors (see below), whose sum is σ = 190115520. Its totient is φ = 78618760.

The previous prime is 129721307. The next prime is 129721351. The reversal of 129721317 is 713127921.

It is not a de Polignac number, because 129721317 - 2⁸ = 129721061 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (129721307) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 178317 + ... + 179042.

It is an arithmetic number, because the mean of its divisors is an integer number (15842960).

Almost surely, 2^129721317 is an apocalyptic number.

It is an amenable number.

129721317 is a deficient number, since it is larger than the sum of its proper divisors (60394203).

129721317 is a wasteful number, since it uses less digits than its factorization.

129721317 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 357384 (or 357373 counting only the distinct ones).

The product of its digits is 5292, while the sum is 33.

The square root of 129721317 is about 11389.5266363445. The cubic root of 129721317 is about 506.2174553686.

The spelling of 129721317 in words is "one hundred twenty-nine million, seven hundred twenty-one thousand, three hundred seventeen".