66956639 has 2 divisors, whose sum is σ = 66956640. Its totient is φ = 66956638.

The previous prime is 66956599. The next prime is 66956671. The reversal of 66956639 is 93665966.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66956639 is a 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 (66956689) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33478319 + 33478320.

It is an arithmetic number, because the mean of its divisors is an integer number (33478320).

Almost surely, 2^66956639 is an apocalyptic number.

66956639 is a deficient number, since it is larger than the sum of its proper divisors (1).

66956639 is an equidigital number, since it uses as much as digits as its factorization.

66956639 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1574640, while the sum is 50.

The square root of 66956639 is about 8182.7036485504. The cubic root of 66956639 is about 406.0671728341.

The spelling of 66956639 in words is "sixty-six million, nine hundred fifty-six thousand, six hundred thirty-nine".