666742761 has 36 divisors (see below), whose sum is σ = 1004630016. Its totient is φ = 426066480.

The previous prime is 666742759. The next prime is 666742819. The reversal of 666742761 is 167247666.

It is a happy number.

It is not a de Polignac number, because 666742761 - 2¹ = 666742759 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666742711) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 1098120 + ... + 1098726.

Almost surely, 2^666742761 is an apocalyptic number.

It is an amenable number.

666742761 is a deficient number, since it is larger than the sum of its proper divisors (337887255).

666742761 is a wasteful number, since it uses less digits than its factorization.

666742761 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 802 (or 768 counting only the distinct ones).

The product of its digits is 508032, while the sum is 45.

The square root of 666742761 is about 25821.3624930986. The cubic root of 666742761 is about 873.6137007333.

The spelling of 666742761 in words is "six hundred sixty-six million, seven hundred forty-two thousand, seven hundred sixty-one".