66643637 has 2 divisors, whose sum is σ = 66643638. Its totient is φ = 66643636.

The previous prime is 66643609. The next prime is 66643649. The reversal of 66643637 is 73634666.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 58583716 + 8059921 = 7654^2 + 2839^2 .

It is a cyclic number.

It is not a de Polignac number, because 66643637 - 2¹⁰ = 66642613 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 66643594 and 66643603.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66643607) 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, 33321818 + 33321819.

It is an arithmetic number, because the mean of its divisors is an integer number (33321819).

Almost surely, 2^66643637 is an apocalyptic number.

It is an amenable number.

66643637 is a deficient number, since it is larger than the sum of its proper divisors (1).

66643637 is an equidigital number, since it uses as much as digits as its factorization.

66643637 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 326592, while the sum is 41.

The square root of 66643637 is about 8163.5554141563. Note that the first 3 decimals coincide. The cubic root of 66643637 is about 405.4334372994.

It can be divided in two parts, 6664 and 3637, that added together give a palindrome (10301).

The spelling of 66643637 in words is "sixty-six million, six hundred forty-three thousand, six hundred thirty-seven".