766591381 has 2 divisors, whose sum is σ = 766591382. Its totient is φ = 766591380.

The previous prime is 766591379. The next prime is 766591409. The reversal of 766591381 is 183195667.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 416527281 + 350064100 = 20409^2 + 18710^2 .

It is a cyclic number.

It is not a de Polignac number, because 766591381 - 2¹ = 766591379 is a prime.

It is a super-2 number, since 2×766591381² = 1175324690846974322, which contains 22 as substring.

Together with 766591379, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (766591321) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 383295690 + 383295691.

It is an arithmetic number, because the mean of its divisors is an integer number (383295691).

Almost surely, 2^766591381 is an apocalyptic number.

It is an amenable number.

766591381 is a deficient number, since it is larger than the sum of its proper divisors (1).

766591381 is an equidigital number, since it uses as much as digits as its factorization.

766591381 is an evil number, because the sum of its binary digits is even.

The product of its digits is 272160, while the sum is 46.

The square root of 766591381 is about 27687.3866769690. The cubic root of 766591381 is about 915.2111672834.

The spelling of 766591381 in words is "seven hundred sixty-six million, five hundred ninety-one thousand, three hundred eighty-one".