716565721 has 2 divisors, whose sum is σ = 716565722. Its totient is φ = 716565720.

The previous prime is 716565709. The next prime is 716565743. The reversal of 716565721 is 127565617.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 547045321 + 169520400 = 23389^2 + 13020^2 .

It is a cyclic number.

It is not a de Polignac number, because 716565721 - 2¹⁵ = 716532953 is a prime.

It is a super-3 number, since 3×716565721³ (a number of 28 digits) contains 333 as substring.

It is not a weakly prime, because it can be changed into another prime (716565701) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 358282860 + 358282861.

It is an arithmetic number, because the mean of its divisors is an integer number (358282861).

Almost surely, 2^716565721 is an apocalyptic number.

It is an amenable number.

716565721 is a deficient number, since it is larger than the sum of its proper divisors (1).

716565721 is an equidigital number, since it uses as much as digits as its factorization.

716565721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 88200, while the sum is 40.

The square root of 716565721 is about 26768.7452264763. The cubic root of 716565721 is about 894.8536410590.

It can be divided in two parts, 71656 and 5721, that added together give a palindrome (77377).

The spelling of 716565721 in words is "seven hundred sixteen million, five hundred sixty-five thousand, seven hundred twenty-one".