66639771 has 12 divisors (see below), whose sum is σ = 105008280. Its totient is φ = 40387680.

The previous prime is 66639751. The next prime is 66639791. The reversal of 66639771 is 17793666.

It is an interprime number because it is at equal distance from previous prime (66639751) and next prime (66639791).

It is not a de Polignac number, because 66639771 - 2¹⁸ = 66377627 is a prime.

It is not an unprimeable number, because it can be changed into a prime (66639751) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 336466 + ... + 336663.

It is an arithmetic number, because the mean of its divisors is an integer number (8750690).

Almost surely, 2^66639771 is an apocalyptic number.

66639771 is a deficient number, since it is larger than the sum of its proper divisors (38368509).

66639771 is a wasteful number, since it uses less digits than its factorization.

66639771 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 673146 (or 673143 counting only the distinct ones).

The product of its digits is 285768, while the sum is 45.

The square root of 66639771 is about 8163.3186266371. The cubic root of 66639771 is about 405.4255974112.

The spelling of 66639771 in words is "sixty-six million, six hundred thirty-nine thousand, seven hundred seventy-one".