129521261 has 2 divisors, whose sum is σ = 129521262. Its totient is φ = 129521260.

The previous prime is 129521213. The next prime is 129521263. The reversal of 129521261 is 162125921.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 116424100 + 13097161 = 10790^2 + 3619^2 .

It is a cyclic number.

It is not a de Polignac number, because 129521261 - 2¹⁴ = 129504877 is a prime.

Together with 129521263, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (129521263) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64760630 + 64760631.

It is an arithmetic number, because the mean of its divisors is an integer number (64760631).

Almost surely, 2^129521261 is an apocalyptic number.

It is an amenable number.

129521261 is a deficient number, since it is larger than the sum of its proper divisors (1).

129521261 is an equidigital number, since it uses as much as digits as its factorization.

129521261 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2160, while the sum is 29.

The square root of 129521261 is about 11380.7407931118. The cubic root of 129521261 is about 505.9570922388.

The spelling of 129521261 in words is "one hundred twenty-nine million, five hundred twenty-one thousand, two hundred sixty-one".