721616491 has 2 divisors, whose sum is σ = 721616492. Its totient is φ = 721616490.

The previous prime is 721616449. The next prime is 721616501. The reversal of 721616491 is 194616127.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 721616491 - 2²³ = 713227883 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 721616491.

It is not a weakly prime, because it can be changed into another prime (721616591) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 360808245 + 360808246.

It is an arithmetic number, because the mean of its divisors is an integer number (360808246).

Almost surely, 2^721616491 is an apocalyptic number.

721616491 is a deficient number, since it is larger than the sum of its proper divisors (1).

721616491 is an equidigital number, since it uses as much as digits as its factorization.

721616491 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 18144, while the sum is 37.

The square root of 721616491 is about 26862.9203736303. The cubic root of 721616491 is about 896.9512026307.

The spelling of 721616491 in words is "seven hundred twenty-one million, six hundred sixteen thousand, four hundred ninety-one".