721616449 has 2 divisors, whose sum is σ = 721616450. Its totient is φ = 721616448.

The previous prime is 721616437. The next prime is 721616491. The reversal of 721616449 is 944616127.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 569538225 + 152078224 = 23865^2 + 12332^2 .

It is a cyclic number.

It is not a de Polignac number, because 721616449 - 2⁷ = 721616321 is a prime.

It is not a weakly prime, because it can be changed into another prime (721616549) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 360808224 + 360808225.

It is an arithmetic number, because the mean of its divisors is an integer number (360808225).

Almost surely, 2^721616449 is an apocalyptic number.

It is an amenable number.

721616449 is a deficient number, since it is larger than the sum of its proper divisors (1).

721616449 is an equidigital number, since it uses as much as digits as its factorization.

721616449 is an evil number, because the sum of its binary digits is even.

The product of its digits is 72576, while the sum is 40.

The square root of 721616449 is about 26862.9195918835. The cubic root of 721616449 is about 896.9511852290.

The spelling of 721616449 in words is "seven hundred twenty-one million, six hundred sixteen thousand, four hundred forty-nine".