1715715721 has 2 divisors, whose sum is σ = 1715715722. Its totient is φ = 1715715720.

The previous prime is 1715715649. The next prime is 1715715731. The reversal of 1715715721 is 1275175171.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1620867600 + 94848121 = 40260^2 + 9739^2 .

It is a cyclic number.

It is not a de Polignac number, because 1715715721 - 2⁷ = 1715715593 is a prime.

It is not a weakly prime, because it can be changed into another prime (1715715731) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 857857860 + 857857861.

It is an arithmetic number, because the mean of its divisors is an integer number (857857861).

Almost surely, 2^1715715721 is an apocalyptic number.

It is an amenable number.

1715715721 is a deficient number, since it is larger than the sum of its proper divisors (1).

1715715721 is an equidigital number, since it uses as much as digits as its factorization.

1715715721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 17150, while the sum is 37.

The square root of 1715715721 is about 41421.1989324307. The cubic root of 1715715721 is about 1197.1496518549.

The spelling of 1715715721 in words is "one billion, seven hundred fifteen million, seven hundred fifteen thousand, seven hundred twenty-one".