129440921 has 2 divisors, whose sum is σ = 129440922. Its totient is φ = 129440920.

The previous prime is 129440897. The next prime is 129440933. The reversal of 129440921 is 129044921.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 66015625 + 63425296 = 8125^2 + 7964^2 .

It is an emirp because it is prime and its reverse (129044921) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 129440921 - 2¹⁰ = 129439897 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (129443921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64720460 + 64720461.

It is an arithmetic number, because the mean of its divisors is an integer number (64720461).

Almost surely, 2^129440921 is an apocalyptic number.

It is an amenable number.

129440921 is a deficient number, since it is larger than the sum of its proper divisors (1).

129440921 is an equidigital number, since it uses as much as digits as its factorization.

129440921 is an evil number, because the sum of its binary digits is even.

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

The square root of 129440921 is about 11377.2105983848. The cubic root of 129440921 is about 505.8524581940.

The spelling of 129440921 in words is "one hundred twenty-nine million, four hundred forty thousand, nine hundred twenty-one".