129138890881 has 81 divisors (see below), whose sum is σ = 179299011843. Its totient is φ = 92628375840.

The previous prime is 129138890873. The next prime is 129138890897. The reversal of 129138890881 is 188098831921.

The square root of 129138890881 is 359359.

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., 19103386225 + 110035504656 = 138215^2 + 331716^2 .

It is not a de Polignac number, because 129138890881 - 2³ = 129138890873 is a prime.

It is a super-2 number, since 2×129138890881² (a number of 23 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (129138890081) by changing a digit.

It is a polite number, since it can be written in 80 ways as a sum of consecutive naturals, for example, 359718180 + ... + 359718538.

Almost surely, 2^129138890881 is an apocalyptic number.

129138890881 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

129138890881 is the 359359-th square number.

129138890881 is the 179680-th centered octagonal number.

It is an amenable number.

129138890881 is a deficient number, since it is larger than the sum of its proper divisors (50160120962).

129138890881 is an equidigital number, since it uses as much as digits as its factorization.

129138890881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 780 (or 390 counting only the distinct ones).

The product of its (nonzero) digits is 1990656, while the sum is 58.

The spelling of 129138890881 in words is "one hundred twenty-nine billion, one hundred thirty-eight million, eight hundred ninety thousand, eight hundred eighty-one".