721708997 has 2 divisors, whose sum is σ = 721708998. Its totient is φ = 721708996.

The previous prime is 721708979. The next prime is 721709029. The reversal of 721708997 is 799807127.

Together with previous prime (721708979) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 469979041 + 251729956 = 21679^2 + 15866^2 .

It is a cyclic number.

It is not a de Polignac number, because 721708997 - 2²⁴ = 704931781 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (721708907) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 360854498 + 360854499.

It is an arithmetic number, because the mean of its divisors is an integer number (360854499).

Almost surely, 2^721708997 is an apocalyptic number.

It is an amenable number.

721708997 is a deficient number, since it is larger than the sum of its proper divisors (1).

721708997 is an equidigital number, since it uses as much as digits as its factorization.

721708997 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 444528, while the sum is 50.

The square root of 721708997 is about 26864.6421342254. The cubic root of 721708997 is about 896.9895285391.

The spelling of 721708997 in words is "seven hundred twenty-one million, seven hundred eight thousand, nine hundred ninety-seven".