66899993 has 4 divisors (see below), whose sum is σ = 66919860. Its totient is φ = 66880128.

The previous prime is 66899983. The next prime is 66899999. The reversal of 66899993 is 39999866.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 30382144 + 36517849 = 5512^2 + 6043^2 .

It is a cyclic number.

It is not a de Polignac number, because 66899993 - 2²⁰ = 65851417 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66899999) 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, 3488 + ... + 12081.

It is an arithmetic number, because the mean of its divisors is an integer number (16729965).

Almost surely, 2^66899993 is an apocalyptic number.

It is an amenable number.

66899993 is a deficient number, since it is larger than the sum of its proper divisors (19867).

66899993 is a wasteful number, since it uses less digits than its factorization.

66899993 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19866.

The product of its digits is 5668704, while the sum is 59.

The square root of 66899993 is about 8179.2415907589. The cubic root of 66899993 is about 405.9526282018.

The spelling of 66899993 in words is "sixty-six million, eight hundred ninety-nine thousand, nine hundred ninety-three".