721316251 has 2 divisors, whose sum is σ = 721316252. Its totient is φ = 721316250.

The previous prime is 721316249. The next prime is 721316257. The reversal of 721316251 is 152613127.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 721316251 - 2¹ = 721316249 is a prime.

Together with 721316249, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (721316257) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 360658125 + 360658126.

It is an arithmetic number, because the mean of its divisors is an integer number (360658126).

Almost surely, 2^721316251 is an apocalyptic number.

721316251 is a deficient number, since it is larger than the sum of its proper divisors (1).

721316251 is an equidigital number, since it uses as much as digits as its factorization.

721316251 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2520, while the sum is 28.

The square root of 721316251 is about 26857.3314199308. The cubic root of 721316251 is about 896.8267884439.

Adding to 721316251 its reverse (152613127), we get a palindrome (873929378).

The spelling of 721316251 in words is "seven hundred twenty-one million, three hundred sixteen thousand, two hundred fifty-one".