766139661 has 64 divisors (see below), whose sum is σ = 1354867200. Its totient is φ = 418618368.

The previous prime is 766139639. The next prime is 766139677. The reversal of 766139661 is 166931667.

It is not a de Polignac number, because 766139661 - 2⁶ = 766139597 is a prime.

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (766139681) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 618735 + ... + 619971.

It is an arithmetic number, because the mean of its divisors is an integer number (21169800).

Almost surely, 2^766139661 is an apocalyptic number.

It is an amenable number.

766139661 is a deficient number, since it is larger than the sum of its proper divisors (588727539).

766139661 is a wasteful number, since it uses less digits than its factorization.

766139661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1395 (or 1389 counting only the distinct ones).

The product of its digits is 244944, while the sum is 45.

The square root of 766139661 is about 27679.2279697249. The cubic root of 766139661 is about 915.0313668366.

The spelling of 766139661 in words is "seven hundred sixty-six million, one hundred thirty-nine thousand, six hundred sixty-one".