764247221 has 4 divisors (see below), whose sum is σ = 766967244. Its totient is φ = 761527200.

The previous prime is 764247217. The next prime is 764247251. The reversal of 764247221 is 122742467.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 122742467 = 23 ⋅5336629.

It can be written as a sum of positive squares in 2 ways, for example, as 230128900 + 534118321 = 15170^2 + 23111^2 .

It is a cyclic number.

It is not a de Polignac number, because 764247221 - 2² = 764247217 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 (764247251) 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, 1359590 + ... + 1360151.

It is an arithmetic number, because the mean of its divisors is an integer number (191741811).

Almost surely, 2^764247221 is an apocalyptic number.

It is an amenable number.

764247221 is a deficient number, since it is larger than the sum of its proper divisors (2720023).

764247221 is a wasteful number, since it uses less digits than its factorization.

764247221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2720022.

The product of its digits is 37632, while the sum is 35.

The square root of 764247221 is about 27645.0216313896. The cubic root of 764247221 is about 914.2773399565.

Adding to 764247221 its reverse (122742467), we get a palindrome (886989688).

The spelling of 764247221 in words is "seven hundred sixty-four million, two hundred forty-seven thousand, two hundred twenty-one".