721625257 has 2 divisors, whose sum is σ = 721625258. Its totient is φ = 721625256.

The previous prime is 721625239. The next prime is 721625279. The reversal of 721625257 is 752526127.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 580039056 + 141586201 = 24084^2 + 11899^2 .

It is an emirp because it is prime and its reverse (752526127) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-721625257 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (721625057) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 360812628 + 360812629.

It is an arithmetic number, because the mean of its divisors is an integer number (360812629).

Almost surely, 2^721625257 is an apocalyptic number.

It is an amenable number.

721625257 is a deficient number, since it is larger than the sum of its proper divisors (1).

721625257 is an equidigital number, since it uses as much as digits as its factorization.

721625257 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 58800, while the sum is 37.

The square root of 721625257 is about 26863.0835348439. The cubic root of 721625257 is about 896.9548345887.

The spelling of 721625257 in words is "seven hundred twenty-one million, six hundred twenty-five thousand, two hundred fifty-seven".