129261820900 has 81 divisors (see below), whose sum is σ = 283534260849. Its totient is φ = 51151052160.

The previous prime is 129261820873. The next prime is 129261820913. The reversal of 129261820900 is 9028162921.

The square root of 129261820900 is 359530.

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

It can be written as a sum of positive squares in 13 ways, for example, as 43675148196 + 85586672704 = 208986^2 + 292552^2 .

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 564461986 + ... + 564462214.

Almost surely, 2^129261820900 is an apocalyptic number.

129261820900 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

129261820900 is the 359530-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 129261820900

129261820900 is an abundant number, since it is smaller than the sum of its proper divisors (154272439949).

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

129261820900 is an equidigital number, since it uses as much as digits as its factorization.

129261820900 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 786 (or 393 counting only the distinct ones).

The product of its (nonzero) digits is 31104, while the sum is 40.

The spelling of 129261820900 in words is "one hundred twenty-nine billion, two hundred sixty-one million, eight hundred twenty thousand, nine hundred".