66208091 has 4 divisors (see below), whose sum is σ = 66850992. Its totient is φ = 65565192.

The previous prime is 66208067. The next prime is 66208097. The reversal of 66208091 is 19080266.

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 66208091 - 2¹⁴ = 66191707 is a prime.

It is a super-2 number, since 2×66208091² = 8767022627728562, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66208097) 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, 321296 + ... + 321501.

It is an arithmetic number, because the mean of its divisors is an integer number (16712748).

Almost surely, 2^66208091 is an apocalyptic number.

66208091 is a deficient number, since it is larger than the sum of its proper divisors (642901).

66208091 is a wasteful number, since it uses less digits than its factorization.

66208091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 642900.

The product of its (nonzero) digits is 5184, while the sum is 32.

The square root of 66208091 is about 8136.8354413740. The cubic root of 66208091 is about 404.5482765156.

The spelling of 66208091 in words is "sixty-six million, two hundred eight thousand, ninety-one".