129721757 has 16 divisors (see below), whose sum is σ = 144529920. Its totient is φ = 115441200.

The previous prime is 129721723. The next prime is 129721783. The reversal of 129721757 is 757127921.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 129721757 - 2⁶ = 129721693 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (129721957) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 126794 + ... + 127812.

It is an arithmetic number, because the mean of its divisors is an integer number (9033120).

Almost surely, 2^129721757 is an apocalyptic number.

It is an amenable number.

129721757 is a deficient number, since it is larger than the sum of its proper divisors (14808163).

129721757 is a wasteful number, since it uses less digits than its factorization.

129721757 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1264.

The product of its digits is 61740, while the sum is 41.

The square root of 129721757 is about 11389.5459523196. The cubic root of 129721757 is about 506.2180277121.

The spelling of 129721757 in words is "one hundred twenty-nine million, seven hundred twenty-one thousand, seven hundred fifty-seven".