66699889 has 3 divisors (see below), whose sum is σ = 66708057. Its totient is φ = 66691722.

The previous prime is 66699847. The next prime is 66699949. The reversal of 66699889 is 98899666.

The square root of 66699889 is 8167.

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

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is not a de Polignac number, because 66699889 - 2⁷ = 66699761 is a prime.

It is a super-2 number, since 2×66699889² = 8897750385224642, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66697889) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 4084 + ... + 12250.

It is an arithmetic number, because the mean of its divisors is an integer number (22236019).

Almost surely, 2^66699889 is an apocalyptic number.

66699889 is the 8167-th square number.

66699889 is the 4084-th centered octagonal number.

It is an amenable number.

66699889 is a deficient number, since it is larger than the sum of its proper divisors (8168).

66699889 is an frugal number, since it uses more digits than its factorization.

66699889 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16334 (or 8167 counting only the distinct ones).

The product of its digits is 10077696, while the sum is 61.

The cubic root of 66699889 is about 405.5474768336.

The spelling of 66699889 in words is "sixty-six million, six hundred ninety-nine thousand, eight hundred eighty-nine".