66201891 has 24 divisors (see below), whose sum is σ = 104143104. Its totient is φ = 37290960.

The previous prime is 66201887. The next prime is 66201899. The reversal of 66201891 is 19810266.

66201891 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 66201891 - 2² = 66201887 is a prime.

It is not an unprimeable number, because it can be changed into a prime (66201899) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 7266 + ... + 13608.

It is an arithmetic number, because the mean of its divisors is an integer number (4339296).

Almost surely, 2^66201891 is an apocalyptic number.

66201891 is a deficient number, since it is larger than the sum of its proper divisors (37941213).

66201891 is a wasteful number, since it uses less digits than its factorization.

66201891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6431 (or 6424 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 33.

The square root of 66201891 is about 8136.4544489599. The cubic root of 66201891 is about 404.5356482624.

The spelling of 66201891 in words is "sixty-six million, two hundred one thousand, eight hundred ninety-one".