129431728 has 10 divisors (see below), whose sum is σ = 250774004. Its totient is φ = 64715856.

The previous prime is 129431719. The next prime is 129431737. The reversal of 129431728 is 827134921.

It is an interprime number because it is at equal distance from previous prime (129431719) and next prime (129431737).

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4044726 + ... + 4044757.

Almost surely, 2^129431728 is an apocalyptic number.

It is an amenable number.

129431728 is a deficient number, since it is larger than the sum of its proper divisors (121342276).

129431728 is an equidigital number, since it uses as much as digits as its factorization.

129431728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8089491 (or 8089485 counting only the distinct ones).

The product of its digits is 24192, while the sum is 37.

The square root of 129431728 is about 11376.8065818137. The cubic root of 129431728 is about 505.8404825589.

The spelling of 129431728 in words is "one hundred twenty-nine million, four hundred thirty-one thousand, seven hundred twenty-eight".