66912091 has 4 divisors (see below), whose sum is σ = 70433800. Its totient is φ = 63390384.

The previous prime is 66912089. The next prime is 66912137. The reversal of 66912091 is 19021966.

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

It is not a de Polignac number, because 66912091 - 2¹ = 66912089 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66912011) 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, 1760826 + ... + 1760863.

It is an arithmetic number, because the mean of its divisors is an integer number (17608450).

Almost surely, 2^66912091 is an apocalyptic number.

66912091 is a deficient number, since it is larger than the sum of its proper divisors (3521709).

66912091 is a wasteful number, since it uses less digits than its factorization.

66912091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3521708.

The product of its (nonzero) digits is 5832, while the sum is 34.

The square root of 66912091 is about 8179.9811124476. The cubic root of 66912091 is about 405.9770971574.

The spelling of 66912091 in words is "sixty-six million, nine hundred twelve thousand, ninety-one".