129721845 has 32 divisors (see below), whose sum is σ = 226934784. Its totient is φ = 62753600.

The previous prime is 129721831. The next prime is 129721847. The reversal of 129721845 is 548127921.

It is not a de Polignac number, because 129721845 - 2⁴ = 129721829 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (129721847) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 141940 + ... + 142850.

It is an arithmetic number, because the mean of its divisors is an integer number (7091712).

Almost surely, 2^129721845 is an apocalyptic number.

129721845 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

129721845 is a deficient number, since it is larger than the sum of its proper divisors (97212939).

129721845 is a wasteful number, since it uses less digits than its factorization.

129721845 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1793.

The product of its digits is 40320, while the sum is 39.

The square root of 129721845 is about 11389.5498155107. The cubic root of 129721845 is about 506.2181421806.

The spelling of 129721845 in words is "one hundred twenty-nine million, seven hundred twenty-one thousand, eight hundred forty-five".