767664221 has 2 divisors, whose sum is σ = 767664222. Its totient is φ = 767664220.

The previous prime is 767664203. The next prime is 767664229. The reversal of 767664221 is 122466767.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 761484025 + 6180196 = 27595^2 + 2486^2 .

It is an emirp because it is prime and its reverse (122466767) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-767664221 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (767664229) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 383832110 + 383832111.

It is an arithmetic number, because the mean of its divisors is an integer number (383832111).

Almost surely, 2^767664221 is an apocalyptic number.

It is an amenable number.

767664221 is a deficient number, since it is larger than the sum of its proper divisors (1).

767664221 is an equidigital number, since it uses as much as digits as its factorization.

767664221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 169344, while the sum is 41.

The square root of 767664221 is about 27706.7540682773. The cubic root of 767664221 is about 915.6379124335.

The spelling of 767664221 in words is "seven hundred sixty-seven million, six hundred sixty-four thousand, two hundred twenty-one".