66138775 has 6 divisors (see below), whose sum is σ = 82012112. Its totient is φ = 52911000.

The previous prime is 66138769. The next prime is 66138811. The reversal of 66138775 is 57783166.

It is not a de Polignac number, because 66138775 - 2³ = 66138767 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1322751 + ... + 1322800.

Almost surely, 2^66138775 is an apocalyptic number.

66138775 is a deficient number, since it is larger than the sum of its proper divisors (15873337).

66138775 is a wasteful number, since it uses less digits than its factorization.

66138775 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2645561 (or 2645556 counting only the distinct ones).

The product of its digits is 211680, while the sum is 43.

The square root of 66138775 is about 8132.5749304879. The cubic root of 66138775 is about 404.4070477544.

The spelling of 66138775 in words is "sixty-six million, one hundred thirty-eight thousand, seven hundred seventy-five".