721708693 has 2 divisors, whose sum is σ = 721708694. Its totient is φ = 721708692.

The previous prime is 721708679. The next prime is 721708727. The reversal of 721708693 is 396807127.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 429401284 + 292307409 = 20722^2 + 17097^2 .

It is an emirp because it is prime and its reverse (396807127) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 721708693 - 2⁵ = 721708661 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (721708093) 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, 360854346 + 360854347.

It is an arithmetic number, because the mean of its divisors is an integer number (360854347).

Almost surely, 2^721708693 is an apocalyptic number.

It is an amenable number.

721708693 is a deficient number, since it is larger than the sum of its proper divisors (1).

721708693 is an equidigital number, since it uses as much as digits as its factorization.

721708693 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 127008, while the sum is 43.

The square root of 721708693 is about 26864.6364762302. The cubic root of 721708693 is about 896.9894025950.

The spelling of 721708693 in words is "seven hundred twenty-one million, seven hundred eight thousand, six hundred ninety-three".