129288821 has 2 divisors, whose sum is σ = 129288822. Its totient is φ = 129288820.

The previous prime is 129288769. The next prime is 129288823. The reversal of 129288821 is 128882921.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 121308196 + 7980625 = 11014^2 + 2825^2 .

It is an emirp because it is prime and its reverse (128882921) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-129288821 is a prime.

Together with 129288823, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (129288823) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64644410 + 64644411.

It is an arithmetic number, because the mean of its divisors is an integer number (64644411).

Almost surely, 2^129288821 is an apocalyptic number.

It is an amenable number.

129288821 is a deficient number, since it is larger than the sum of its proper divisors (1).

129288821 is an equidigital number, since it uses as much as digits as its factorization.

129288821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 36864, while the sum is 41.

The square root of 129288821 is about 11370.5242183463. The cubic root of 129288821 is about 505.6542459794.

The spelling of 129288821 in words is "one hundred twenty-nine million, two hundred eighty-eight thousand, eight hundred twenty-one".