66400493 has 2 divisors, whose sum is σ = 66400494. Its totient is φ = 66400492.

The previous prime is 66400489. The next prime is 66400567. The reversal of 66400493 is 39400466.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 42994249 + 23406244 = 6557^2 + 4838^2 .

It is a cyclic number.

It is not a de Polignac number, because 66400493 - 2² = 66400489 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66400403) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33200246 + 33200247.

It is an arithmetic number, because the mean of its divisors is an integer number (33200247).

Almost surely, 2^66400493 is an apocalyptic number.

It is an amenable number.

66400493 is a deficient number, since it is larger than the sum of its proper divisors (1).

66400493 is an equidigital number, since it uses as much as digits as its factorization.

66400493 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 15552, while the sum is 32.

The square root of 66400493 is about 8148.6497654519. The cubic root of 66400493 is about 404.9397725814.

The spelling of 66400493 in words is "sixty-six million, four hundred thousand, four hundred ninety-three".