66975887209 has 27 divisors (see below), whose sum is σ = 85662896823. Its totient is φ = 52173475200.

The previous prime is 66975887203. The next prime is 66975887233. The reversal of 66975887209 is 90278857966.

The square root of 66975887209 is 258797.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 50241877609 + 16734009600 = 224147^2 + 129360^2 .

It is not a de Polignac number, because 66975887209 - 2¹⁵ = 66975854441 is a prime.

It is not an unprimeable number, because it can be changed into a prime (66975887203) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 19925689 + ... + 19929049.

Almost surely, 2^66975887209 is an apocalyptic number.

66975887209 is the 258797-th square number.

66975887209 is the 129399-th centered octagonal number.

It is an amenable number.

66975887209 is a deficient number, since it is larger than the sum of its proper divisors (18687009614).

66975887209 is an frugal number, since it uses more digits than its factorization.

66975887209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6758 (or 3379 counting only the distinct ones).

The product of its (nonzero) digits is 91445760, while the sum is 67.

The spelling of 66975887209 in words is "sixty-six billion, nine hundred seventy-five million, eight hundred eighty-seven thousand, two hundred nine".