66972891 has 16 divisors (see below), whose sum is σ = 94227840. Its totient is φ = 42194880.

The previous prime is 66972889. The next prime is 66972959. The reversal of 66972891 is 19827966.

It is not a de Polignac number, because 66972891 - 2¹ = 66972889 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 66972891.

It is not an unprimeable number, because it can be changed into a prime (66972811) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 26791 + ... + 29183.

It is an arithmetic number, because the mean of its divisors is an integer number (5889240).

Almost surely, 2^66972891 is an apocalyptic number.

66972891 is a deficient number, since it is larger than the sum of its proper divisors (27254949).

66972891 is a wasteful number, since it uses less digits than its factorization.

66972891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2906.

The product of its digits is 326592, while the sum is 48.

The square root of 66972891 is about 8183.6966586012. The cubic root of 66972891 is about 406.1000242930.

The spelling of 66972891 in words is "sixty-six million, nine hundred seventy-two thousand, eight hundred ninety-one".