66206639 has 2 divisors, whose sum is σ = 66206640. Its totient is φ = 66206638.

The previous prime is 66206617. The next prime is 66206663. The reversal of 66206639 is 93660266.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66206639 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66206689) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33103319 + 33103320.

It is an arithmetic number, because the mean of its divisors is an integer number (33103320).

Almost surely, 2^66206639 is an apocalyptic number.

66206639 is a deficient number, since it is larger than the sum of its proper divisors (1).

66206639 is an equidigital number, since it uses as much as digits as its factorization.

66206639 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 69984, while the sum is 38.

The square root of 66206639 is about 8136.7462170084. The cubic root of 66206639 is about 404.5453191309.

The spelling of 66206639 in words is "sixty-six million, two hundred six thousand, six hundred thirty-nine".