66491819 has 2 divisors, whose sum is σ = 66491820. Its totient is φ = 66491818.

The previous prime is 66491783. The next prime is 66491837. The reversal of 66491819 is 91819466.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 66491819 - 2⁸ = 66491563 is a prime.

It is a super-2 number, since 2×66491819² = 8842323987857522, 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 66491819.

It is not a weakly prime, because it can be changed into another prime (66491899) 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, 33245909 + 33245910.

It is an arithmetic number, because the mean of its divisors is an integer number (33245910).

Almost surely, 2^66491819 is an apocalyptic number.

66491819 is a deficient number, since it is larger than the sum of its proper divisors (1).

66491819 is an equidigital number, since it uses as much as digits as its factorization.

66491819 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 93312, while the sum is 44.

The square root of 66491819 is about 8154.2515904281. The cubic root of 66491819 is about 405.1253364047.

The spelling of 66491819 in words is "sixty-six million, four hundred ninety-one thousand, eight hundred nineteen".