66893991 has 4 divisors (see below), whose sum is σ = 89191992. Its totient is φ = 44595992.

The previous prime is 66893987. The next prime is 66894007. The reversal of 66893991 is 19939866.

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 66893991 - 2² = 66893987 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66893921) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11148996 + ... + 11149001.

It is an arithmetic number, because the mean of its divisors is an integer number (22297998).

Almost surely, 2^66893991 is an apocalyptic number.

66893991 is a deficient number, since it is larger than the sum of its proper divisors (22298001).

66893991 is a wasteful number, since it uses less digits than its factorization.

66893991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22298000.

The product of its digits is 629856, while the sum is 51.

The square root of 66893991 is about 8178.8746780960. The cubic root of 66893991 is about 405.9404876896.

The spelling of 66893991 in words is "sixty-six million, eight hundred ninety-three thousand, nine hundred ninety-one".