764587661 has 4 divisors (see below), whose sum is σ = 764798172. Its totient is φ = 764377152.

The previous prime is 764587613. The next prime is 764587673. The reversal of 764587661 is 166785467.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 166785467 = 29 ⋅5751223.

It can be written as a sum of positive squares in 2 ways, for example, as 317053636 + 447534025 = 17806^2 + 21155^2 .

It is a cyclic number.

It is not a de Polignac number, because 764587661 - 2¹⁸ = 764325517 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (764587561) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 99710 + ... + 107103.

It is an arithmetic number, because the mean of its divisors is an integer number (191199543).

Almost surely, 2^764587661 is an apocalyptic number.

It is an amenable number.

764587661 is a deficient number, since it is larger than the sum of its proper divisors (210511).

764587661 is a wasteful number, since it uses less digits than its factorization.

764587661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 210510.

The product of its digits is 1693440, while the sum is 50.

The square root of 764587661 is about 27651.1782931578. The cubic root of 764587661 is about 914.4130771732.

The spelling of 764587661 in words is "seven hundred sixty-four million, five hundred eighty-seven thousand, six hundred sixty-one".