129521961 has 6 divisors (see below), whose sum is σ = 187087290. Its totient is φ = 86347968.

The previous prime is 129521893. The next prime is 129521969. The reversal of 129521961 is 169125921.

129521961 is a `hidden beast` number, since 129 + 521 + 9 + 6 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 104960025 + 24561936 = 10245^2 + 4956^2 .

It is not a de Polignac number, because 129521961 - 2⁹ = 129521449 is a prime.

It is not an unprimeable number, because it can be changed into a prime (129521969) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 7195656 + ... + 7195673.

It is an arithmetic number, because the mean of its divisors is an integer number (31181215).

Almost surely, 2^129521961 is an apocalyptic number.

It is an amenable number.

129521961 is a deficient number, since it is larger than the sum of its proper divisors (57565329).

129521961 is a wasteful number, since it uses less digits than its factorization.

129521961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14391335 (or 14391332 counting only the distinct ones).

The product of its digits is 9720, while the sum is 36.

The square root of 129521961 is about 11380.7715467801. The cubic root of 129521961 is about 505.9580037219.

The spelling of 129521961 in words is "one hundred twenty-nine million, five hundred twenty-one thousand, nine hundred sixty-one".