721646129 has 2 divisors, whose sum is σ = 721646130. Its totient is φ = 721646128.

The previous prime is 721646083. The next prime is 721646221. The reversal of 721646129 is 921646127.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 721029904 + 616225 = 26852^2 + 785^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-721646129 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 721646092 and 721646101.

It is not a weakly prime, because it can be changed into another prime (721646929) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 360823064 + 360823065.

It is an arithmetic number, because the mean of its divisors is an integer number (360823065).

Almost surely, 2^721646129 is an apocalyptic number.

It is an amenable number.

721646129 is a deficient number, since it is larger than the sum of its proper divisors (1).

721646129 is an equidigital number, since it uses as much as digits as its factorization.

721646129 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 36288, while the sum is 38.

The square root of 721646129 is about 26863.4720205710. The cubic root of 721646129 is about 896.9634822261.

The spelling of 721646129 in words is "seven hundred twenty-one million, six hundred forty-six thousand, one hundred twenty-nine".