721645607 has 2 divisors, whose sum is σ = 721645608. Its totient is φ = 721645606.

The previous prime is 721645583. The next prime is 721645609. The reversal of 721645607 is 706546127.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 721645607 - 2¹⁸ = 721383463 is a prime.

Together with 721645609, 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 (721645609) 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, 360822803 + 360822804.

It is an arithmetic number, because the mean of its divisors is an integer number (360822804).

Almost surely, 2^721645607 is an apocalyptic number.

721645607 is a deficient number, since it is larger than the sum of its proper divisors (1).

721645607 is an equidigital number, since it uses as much as digits as its factorization.

721645607 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 70560, while the sum is 38.

The square root of 721645607 is about 26863.4623047737. The cubic root of 721645607 is about 896.9632659544.

The spelling of 721645607 in words is "seven hundred twenty-one million, six hundred forty-five thousand, six hundred seven".