7666639 has 2 divisors, whose sum is σ = 7666640. Its totient is φ = 7666638.

The previous prime is 7666621. The next prime is 7666661. The reversal of 7666639 is 9366667.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-7666639 is a prime.

7666639 is a lucky number.

It is a junction number, because it is equal to n+sod(n) for n = 7666595 and 7666604.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (7666619) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3833319 + 3833320.

It is an arithmetic number, because the mean of its divisors is an integer number (3833320).

Almost surely, 2^7666639 is an apocalyptic number.

7666639 is a deficient number, since it is larger than the sum of its proper divisors (1).

7666639 is an equidigital number, since it uses as much as digits as its factorization.

7666639 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 244944, while the sum is 43.

The square root of 7666639 is about 2768.8696249553. The cubic root of 7666639 is about 197.1824861323.

The spelling of 7666639 in words is "seven million, six hundred sixty-six thousand, six hundred thirty-nine".