129521969 has 2 divisors, whose sum is σ = 129521970. Its totient is φ = 129521968.

The previous prime is 129521893. The next prime is 129522013. The reversal of 129521969 is 969125921.

It is an a-pointer prime, because the next prime (129522013) can be obtained adding 129521969 to its sum of digits (44).

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 108472225 + 21049744 = 10415^2 + 4588^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-129521969 is a prime.

It is a super-2 number, since 2×129521969² = 33551880907273922, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (129521269) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64760984 + 64760985.

It is an arithmetic number, because the mean of its divisors is an integer number (64760985).

Almost surely, 2^129521969 is an apocalyptic number.

It is an amenable number.

129521969 is a deficient number, since it is larger than the sum of its proper divisors (1).

129521969 is an equidigital number, since it uses as much as digits as its factorization.

129521969 is an evil number, because the sum of its binary digits is even.

The product of its digits is 87480, while the sum is 44.

The square root of 129521969 is about 11380.7718982501. The cubic root of 129521969 is about 505.9580141388.

The spelling of 129521969 in words is "one hundred twenty-nine million, five hundred twenty-one thousand, nine hundred sixty-nine".