666637 has 2 divisors, whose sum is σ = 666638. Its totient is φ = 666636.

The previous prime is 666607. The next prime is 666643. The reversal of 666637 is 736666.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 617796 + 48841 = 786^2 + 221^2 .

It is a cyclic number.

It is not a de Polignac number, because 666637 - 2¹¹ = 664589 is a prime.

666637 is a lucky number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (666607) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333318 + 333319.

It is an arithmetic number, because the mean of its divisors is an integer number (333319).

2⁶⁶⁶⁶³⁷ is an apocalyptic number.

It is an amenable number.

666637 is a deficient number, since it is larger than the sum of its proper divisors (1).

666637 is an equidigital number, since it uses as much as digits as its factorization.

666637 is an evil number, because the sum of its binary digits is even.

The product of its digits is 27216, while the sum is 34.

The square root of 666637 is about 816.4784136767. The cubic root of 666637 is about 87.3567506434.

It can be divided in two parts, 6666 and 37, that multiplied together give a palindrome (246642).

The spelling of 666637 in words is "six hundred sixty-six thousand, six hundred thirty-seven".