129878789769 has 45 divisors (see below), whose sum is σ = 202935285399. Its totient is φ = 82773686160.

The previous prime is 129878789737. The next prime is 129878789771. The reversal of 129878789769 is 967987878921.

It is a happy number.

The square root of 129878789769 is 360387.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 149157369 + 129729632400 = 12213^2 + 360180^2 .

It is not a de Polignac number, because 129878789769 - 2⁵ = 129878789737 is a prime.

It is a super-2 number, since 2×129878789769² (a number of 23 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (81).

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (129878782769) by changing a digit.

It is a polite number, since it can be written in 44 ways as a sum of consecutive naturals, for example, 74599239 + ... + 74600979.

Almost surely, 2^129878789769 is an apocalyptic number.

129878789769 is the 360387-th square number.

129878789769 is the 180194-th centered octagonal number.

It is an amenable number.

129878789769 is a deficient number, since it is larger than the sum of its proper divisors (73056495630).

129878789769 is an frugal number, since it uses more digits than its factorization.

129878789769 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3540 (or 1767 counting only the distinct ones).

The product of its digits is 1536288768, while the sum is 81.

Multiplying 129878789769 by its sum of digits (81), we get a square (10520181971289 = 3243483²).

129878789769 divided by its sum of digits (81) gives a square (1603441849 = 40043²).

The spelling of 129878789769 in words is "one hundred twenty-nine billion, eight hundred seventy-eight million, seven hundred eighty-nine thousand, seven hundred sixty-nine".