66623639 has 2 divisors, whose sum is σ = 66623640. Its totient is φ = 66623638.

The previous prime is 66623611. The next prime is 66623677. The reversal of 66623639 is 93632666.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66623639 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 66623596 and 66623605.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66623839) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33311819 + 33311820.

It is an arithmetic number, because the mean of its divisors is an integer number (33311820).

Almost surely, 2^66623639 is an apocalyptic number.

66623639 is a deficient number, since it is larger than the sum of its proper divisors (1).

66623639 is an equidigital number, since it uses as much as digits as its factorization.

66623639 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 209952, while the sum is 41.

The square root of 66623639 is about 8162.3304882858. The cubic root of 66623639 is about 405.3928799440.

It can be divided in two parts, 6662 and 3639, that added together give a palindrome (10301).

The spelling of 66623639 in words is "sixty-six million, six hundred twenty-three thousand, six hundred thirty-nine".