129747978 has 48 divisors (see below), whose sum is σ = 299557440. Its totient is φ = 40445568.

The previous prime is 129747973. The next prime is 129747983. The reversal of 129747978 is 879747921.

129747978 is a `hidden beast` number, since 12 + 97 + 479 + 78 = 666.

It is an interprime number because it is at equal distance from previous prime (129747973) and next prime (129747983).

It is not an unprimeable number, because it can be changed into a prime (129747973) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 49833 + ... + 52371.

It is an arithmetic number, because the mean of its divisors is an integer number (6240780).

Almost surely, 2^129747978 is an apocalyptic number.

129747978 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 129747978, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (149778720).

129747978 is an abundant number, since it is smaller than the sum of its proper divisors (169809462).

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

129747978 is a wasteful number, since it uses less digits than its factorization.

129747978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2731 (or 2728 counting only the distinct ones).

The product of its digits is 1778112, while the sum is 54.

The square root of 129747978 is about 11390.6969935996. The cubic root of 129747978 is about 506.2521331414.

The spelling of 129747978 in words is "one hundred twenty-nine million, seven hundred forty-seven thousand, nine hundred seventy-eight".