765660721 has 16 divisors (see below), whose sum is σ = 917046400. Its totient is φ = 638532720.

The previous prime is 765660683. The next prime is 765660743. The reversal of 765660721 is 127066567.

It is a happy number.

It is not a de Polignac number, because 765660721 - 2¹⁵ = 765627953 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (765660781) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 17475 + ... + 42856.

It is an arithmetic number, because the mean of its divisors is an integer number (57315400).

Almost surely, 2^765660721 is an apocalyptic number.

It is an amenable number.

765660721 is a deficient number, since it is larger than the sum of its proper divisors (151385679).

765660721 is an equidigital number, since it uses as much as digits as its factorization.

765660721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 60389 (or 60375 counting only the distinct ones).

The product of its (nonzero) digits is 105840, while the sum is 40.

The square root of 765660721 is about 27670.5750030606. The cubic root of 765660721 is about 914.8406546651.

The spelling of 765660721 in words is "seven hundred sixty-five million, six hundred sixty thousand, seven hundred twenty-one".