66750639 has 4 divisors (see below), whose sum is σ = 89000856. Its totient is φ = 44500424.

The previous prime is 66750637. The next prime is 66750661. The reversal of 66750639 is 93605766.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 66750639 - 2¹ = 66750637 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 66750639.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66750637) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11125104 + ... + 11125109.

It is an arithmetic number, because the mean of its divisors is an integer number (22250214).

Almost surely, 2^66750639 is an apocalyptic number.

66750639 is a deficient number, since it is larger than the sum of its proper divisors (22250217).

66750639 is a wasteful number, since it uses less digits than its factorization.

66750639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22250216.

The product of its (nonzero) digits is 204120, while the sum is 42.

The square root of 66750639 is about 8170.1064252554. The cubic root of 66750639 is about 405.6503071731.

The spelling of 66750639 in words is "sixty-six million, seven hundred fifty thousand, six hundred thirty-nine".