315721643 has 2 divisors, whose sum is σ = 315721644. Its totient is φ = 315721642.

The previous prime is 315721633. The next prime is 315721669. The reversal of 315721643 is 346127513.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 315721643 - 2⁸ = 315721387 is a prime.

It is not a weakly prime, because it can be changed into another prime (315721633) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 157860821 + 157860822.

It is an arithmetic number, because the mean of its divisors is an integer number (157860822).

Almost surely, 2^315721643 is an apocalyptic number.

315721643 is a deficient number, since it is larger than the sum of its proper divisors (1).

315721643 is an equidigital number, since it uses as much as digits as its factorization.

315721643 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 15120, while the sum is 32.

The square root of 315721643 is about 17768.5577073661. The cubic root of 315721643 is about 680.9284053125.

The spelling of 315721643 in words is "three hundred fifteen million, seven hundred twenty-one thousand, six hundred forty-three".