129731780 has 12 divisors (see below), whose sum is σ = 272436780. Its totient is φ = 51892704.

The previous prime is 129731759. The next prime is 129731783. The reversal of 129731780 is 87137921.

It can be written as a sum of positive squares in 2 ways, for example, as 77862976 + 51868804 = 8824^2 + 7202^2 .

It is not an unprimeable number, because it can be changed into a prime (129731783) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3243275 + ... + 3243314.

It is an arithmetic number, because the mean of its divisors is an integer number (22703065).

Almost surely, 2^129731780 is an apocalyptic number.

129731780 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

129731780 is an abundant number, since it is smaller than the sum of its proper divisors (142705000).

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

129731780 is a wasteful number, since it uses less digits than its factorization.

129731780 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6486598 (or 6486596 counting only the distinct ones).

The product of its (nonzero) digits is 21168, while the sum is 38.

The square root of 129731780 is about 11389.9859525813. The cubic root of 129731780 is about 506.2310650846.

It can be divided in two parts, 1297 and 31780, that multiplied together give a triangular number (41218660 = T₉₀₇₉).

The spelling of 129731780 in words is "one hundred twenty-nine million, seven hundred thirty-one thousand, seven hundred eighty".