66409855 has 16 divisors (see below), whose sum is σ = 86028480. Its totient is φ = 49063168.

The previous prime is 66409853. The next prime is 66409859. The reversal of 66409855 is 55890466.

66409855 is nontrivially palindromic in base 4.

It is a cyclic number.

It is not a de Polignac number, because 66409855 - 2¹ = 66409853 is a prime.

It is a super-2 number, since 2×66409855² = 8820537682242050, which contains 22 as substring.

It is a zygodrome in base 4.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66409853) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6622 + ... + 13291.

It is an arithmetic number, because the mean of its divisors is an integer number (5376780).

Almost surely, 2^66409855 is an apocalyptic number.

66409855 is a deficient number, since it is larger than the sum of its proper divisors (19618625).

66409855 is a wasteful number, since it uses less digits than its factorization.

66409855 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19970.

The product of its (nonzero) digits is 259200, while the sum is 43.

The square root of 66409855 is about 8149.2241962042. The cubic root of 66409855 is about 404.9588029019.

The spelling of 66409855 in words is "sixty-six million, four hundred nine thousand, eight hundred fifty-five".