66101891 has 2 divisors, whose sum is σ = 66101892. Its totient is φ = 66101890.

The previous prime is 66101887. The next prime is 66101897. The reversal of 66101891 is 19810166.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 66101891 - 2² = 66101887 is a prime.

It is not a weakly prime, because it can be changed into another prime (66101897) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33050945 + 33050946.

It is an arithmetic number, because the mean of its divisors is an integer number (33050946).

Almost surely, 2^66101891 is an apocalyptic number.

66101891 is a deficient number, since it is larger than the sum of its proper divisors (1).

66101891 is an equidigital number, since it uses as much as digits as its factorization.

66101891 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2592, while the sum is 32.

The square root of 66101891 is about 8130.3069437752. The cubic root of 66101891 is about 404.3318577558.

The spelling of 66101891 in words is "sixty-six million, one hundred one thousand, eight hundred ninety-one".