66091231 has 2 divisors, whose sum is σ = 66091232. Its totient is φ = 66091230.

The previous prime is 66091217. The next prime is 66091237. The reversal of 66091231 is 13219066.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 66091231 - 2¹⁵ = 66058463 is a prime.

It is a super-2 number, since 2×66091231² = 8736101630190722, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 66091231.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66091237) 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 as a sum of consecutive naturals, namely, 33045615 + 33045616.

It is an arithmetic number, because the mean of its divisors is an integer number (33045616).

Almost surely, 2^66091231 is an apocalyptic number.

66091231 is a deficient number, since it is larger than the sum of its proper divisors (1).

66091231 is an equidigital number, since it uses as much as digits as its factorization.

66091231 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1944, while the sum is 28.

The square root of 66091231 is about 8129.6513455375. The cubic root of 66091231 is about 404.3101215682.

The spelling of 66091231 in words is "sixty-six million, ninety-one thousand, two hundred thirty-one".