129661421 has 2 divisors, whose sum is σ = 129661422. Its totient is φ = 129661420.

The previous prime is 129661387. The next prime is 129661429. The reversal of 129661421 is 124166921.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 112063396 + 17598025 = 10586^2 + 4195^2 .

It is a cyclic number.

It is not a de Polignac number, because 129661421 - 2²⁶ = 62552557 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (129661429) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64830710 + 64830711.

It is an arithmetic number, because the mean of its divisors is an integer number (64830711).

Almost surely, 2^129661421 is an apocalyptic number.

It is an amenable number.

129661421 is a deficient number, since it is larger than the sum of its proper divisors (1).

129661421 is an equidigital number, since it uses as much as digits as its factorization.

129661421 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5184, while the sum is 32.

The square root of 129661421 is about 11386.8968995069. The cubic root of 129661421 is about 506.1395317367.

The spelling of 129661421 in words is "one hundred twenty-nine million, six hundred sixty-one thousand, four hundred twenty-one".