129921768 has 24 divisors (see below), whose sum is σ = 351871650. Its totient is φ = 43307232.

The previous prime is 129921761. The next prime is 129921811. The reversal of 129921768 is 867129921.

It can be written as a sum of positive squares in only one way, i.e., 77475204 + 52446564 = 8802^2 + 7242^2 .

It is a tau number, because it is divible by the number of its divisors (24).

It is not an unprimeable number, because it can be changed into a prime (129921761) 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 in 5 ways as a sum of consecutive naturals, for example, 902163 + ... + 902306.

Almost surely, 2^129921768 is an apocalyptic number.

129921768 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is an amenable number.

129921768 is an abundant number, since it is smaller than the sum of its proper divisors (221949882).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

129921768 is a wasteful number, since it uses less digits than its factorization.

129921768 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1804481 (or 1804474 counting only the distinct ones).

The product of its digits is 108864, while the sum is 45.

The square root of 129921768 is about 11398.3230345521. The cubic root of 129921768 is about 506.4780642290.

The spelling of 129921768 in words is "one hundred twenty-nine million, nine hundred twenty-one thousand, seven hundred sixty-eight".