66688894 has 4 divisors (see below), whose sum is σ = 100033344. Its totient is φ = 33344446.

The previous prime is 66688873. The next prime is 66688903. The reversal of 66688894 is 49888666.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 49888666 = 2 ⋅24944333.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 16672222 + ... + 16672225.

It is an arithmetic number, because the mean of its divisors is an integer number (25008336).

Almost surely, 2^66688894 is an apocalyptic number.

66688894 is a deficient number, since it is larger than the sum of its proper divisors (33344450).

66688894 is a wasteful number, since it uses less digits than its factorization.

66688894 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33344449.

The product of its digits is 3981312, while the sum is 55.

The square root of 66688894 is about 8166.3268364669. The cubic root of 66688894 is about 405.5251917413.

The spelling of 66688894 in words is "sixty-six million, six hundred eighty-eight thousand, eight hundred ninety-four".