721793257 has 2 divisors, whose sum is σ = 721793258. Its totient is φ = 721793256.

The previous prime is 721793249. The next prime is 721793269. The reversal of 721793257 is 752397127.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 694638736 + 27154521 = 26356^2 + 5211^2 .

It is an emirp because it is prime and its reverse (752397127) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 721793257 - 2³ = 721793249 is a prime.

It is not a weakly prime, because it can be changed into another prime (721793207) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 360896628 + 360896629.

It is an arithmetic number, because the mean of its divisors is an integer number (360896629).

Almost surely, 2^721793257 is an apocalyptic number.

It is an amenable number.

721793257 is a deficient number, since it is larger than the sum of its proper divisors (1).

721793257 is an equidigital number, since it uses as much as digits as its factorization.

721793257 is an evil number, because the sum of its binary digits is even.

The product of its digits is 185220, while the sum is 43.

The square root of 721793257 is about 26866.2103207728. The cubic root of 721793257 is about 897.0244352198.

The spelling of 721793257 in words is "seven hundred twenty-one million, seven hundred ninety-three thousand, two hundred fifty-seven".