129125621 has 2 divisors, whose sum is σ = 129125622. Its totient is φ = 129125620.

The previous prime is 129125573. The next prime is 129125627. The reversal of 129125621 is 126521921.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 127464100 + 1661521 = 11290^2 + 1289^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-129125621 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (129125627) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64562810 + 64562811.

It is an arithmetic number, because the mean of its divisors is an integer number (64562811).

Almost surely, 2^129125621 is an apocalyptic number.

It is an amenable number.

129125621 is a deficient number, since it is larger than the sum of its proper divisors (1).

129125621 is an equidigital number, since it uses as much as digits as its factorization.

129125621 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 129125621 is about 11363.3455020958. The cubic root of 129125621 is about 505.4413956101.

The spelling of 129125621 in words is "one hundred twenty-nine million, one hundred twenty-five thousand, six hundred twenty-one".