766661761 has 4 divisors (see below), whose sum is σ = 807012400. Its totient is φ = 726311124.

The previous prime is 766661759. The next prime is 766661803. The reversal of 766661761 is 167166667.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 167166667 = 379 ⋅441073.

It is a cyclic number.

It is not a de Polignac number, because 766661761 - 2¹ = 766661759 is a prime.

It is a super-2 number, since 2×766661761² = 1175540511559242242, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (766661711) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 20175291 + ... + 20175328.

It is an arithmetic number, because the mean of its divisors is an integer number (201753100).

Almost surely, 2^766661761 is an apocalyptic number.

It is an amenable number.

766661761 is a deficient number, since it is larger than the sum of its proper divisors (40350639).

766661761 is a wasteful number, since it uses less digits than its factorization.

766661761 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40350638.

The product of its digits is 381024, while the sum is 46.

The square root of 766661761 is about 27688.6576236552. The cubic root of 766661761 is about 915.2391746384.

The spelling of 766661761 in words is "seven hundred sixty-six million, six hundred sixty-one thousand, seven hundred sixty-one".