764640521 has 2 divisors, whose sum is σ = 764640522. Its totient is φ = 764640520.

The previous prime is 764640517. The next prime is 764640523. The reversal of 764640521 is 125046467.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 729594121 + 35046400 = 27011^2 + 5920^2 .

It is a cyclic number.

It is not a de Polignac number, because 764640521 - 2² = 764640517 is a prime.

Together with 764640523, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (764640523) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 382320260 + 382320261.

It is an arithmetic number, because the mean of its divisors is an integer number (382320261).

Almost surely, 2^764640521 is an apocalyptic number.

It is an amenable number.

764640521 is a deficient number, since it is larger than the sum of its proper divisors (1).

764640521 is an equidigital number, since it uses as much as digits as its factorization.

764640521 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 40320, while the sum is 35.

The square root of 764640521 is about 27652.1341129396. The cubic root of 764640521 is about 914.4341494295.

Adding to 764640521 its reverse (125046467), we get a palindrome (889686988).

The spelling of 764640521 in words is "seven hundred sixty-four million, six hundred forty thousand, five hundred twenty-one".