7666661 has 2 divisors, whose sum is σ = 7666662. Its totient is φ = 7666660.

The previous prime is 7666639. The next prime is 7666667. The reversal of 7666661 is 1666667.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 6300100 + 1366561 = 2510^2 + 1169^2 .

It is a cyclic number.

It is not a de Polignac number, because 7666661 - 2⁶ = 7666597 is a prime.

It is a Chen prime.

It is a nialpdrome in base 10.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (7666667) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3833330 + 3833331.

It is an arithmetic number, because the mean of its divisors is an integer number (3833331).

Almost surely, 2^7666661 is an apocalyptic number.

It is an amenable number.

7666661 is a deficient number, since it is larger than the sum of its proper divisors (1).

7666661 is an equidigital number, since it uses as much as digits as its factorization.

7666661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 54432, while the sum is 38.

The square root of 7666661 is about 2768.8735976928. The cubic root of 7666661 is about 197.1826747421.

It can be divided in two parts, 766666 and 1, that added together give a palindrome (766667).

The spelling of 7666661 in words is "seven million, six hundred sixty-six thousand, six hundred sixty-one".