721003391 has 2 divisors, whose sum is σ = 721003392. Its totient is φ = 721003390.

The previous prime is 721003373. The next prime is 721003397. The reversal of 721003391 is 193300127.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 721003391 - 2²² = 716809087 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 721003391.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (721003397) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 360501695 + 360501696.

It is an arithmetic number, because the mean of its divisors is an integer number (360501696).

Almost surely, 2^721003391 is an apocalyptic number.

721003391 is a deficient number, since it is larger than the sum of its proper divisors (1).

721003391 is an equidigital number, since it uses as much as digits as its factorization.

721003391 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1134, while the sum is 26.

The square root of 721003391 is about 26851.5063078405. The cubic root of 721003391 is about 896.6971080139.

The spelling of 721003391 in words is "seven hundred twenty-one million, three thousand, three hundred ninety-one".