66639523 has 2 divisors, whose sum is σ = 66639524. Its totient is φ = 66639522.

The previous prime is 66639509. The next prime is 66639527. The reversal of 66639523 is 32593666.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66639523 is a prime.

It is not a weakly prime, because it can be changed into another prime (66639527) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33319761 + 33319762.

It is an arithmetic number, because the mean of its divisors is an integer number (33319762).

Almost surely, 2^66639523 is an apocalyptic number.

66639523 is a deficient number, since it is larger than the sum of its proper divisors (1).

66639523 is an equidigital number, since it uses as much as digits as its factorization.

66639523 is an evil number, because the sum of its binary digits is even.

The product of its digits is 174960, while the sum is 40.

The square root of 66639523 is about 8163.3034367222. The cubic root of 66639523 is about 405.4250944800.

The spelling of 66639523 in words is "sixty-six million, six hundred thirty-nine thousand, five hundred twenty-three".