7811520007666 has 16 divisors (see below), whose sum is σ = 11826949638168. Its totient is φ = 3869364150400.

The previous prime is 7811520007661. The next prime is 7811520007667. The reversal of 7811520007666 is 6667000251187.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 7777210225225 + 34309782441 = 2788765^2 + 185229^2 .

It is a super-2 number, since 2×7811520007666² (a number of 27 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (7811520007661) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 40074745 + ... + 40269196.

Almost surely, 2^{7811520007666} is an apocalyptic number.

7811520007666 is a deficient number, since it is larger than the sum of its proper divisors (4015429630502).

7811520007666 is a wasteful number, since it uses less digits than its factorization.

7811520007666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 80344397.

The product of its (nonzero) digits is 846720, while the sum is 49.

The spelling of 7811520007666 in words is "seven trillion, eight hundred eleven billion, five hundred twenty million, seven thousand, six hundred sixty-six".