66550399 has 2 divisors, whose sum is σ = 66550400. Its totient is φ = 66550398.

The previous prime is 66550327. The next prime is 66550409. The reversal of 66550399 is 99305566.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 66550399 - 2⁹ = 66549887 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66550199) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33275199 + 33275200.

It is an arithmetic number, because the mean of its divisors is an integer number (33275200).

Almost surely, 2^66550399 is an apocalyptic number.

66550399 is a deficient number, since it is larger than the sum of its proper divisors (1).

66550399 is an equidigital number, since it uses as much as digits as its factorization.

66550399 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 218700, while the sum is 43.

The square root of 66550399 is about 8157.8427908363. The cubic root of 66550399 is about 405.2442747268.

The spelling of 66550399 in words is "sixty-six million, five hundred fifty thousand, three hundred ninety-nine".