66218890 has 16 divisors (see below), whose sum is σ = 123304680. Its totient is φ = 25574080.

The previous prime is 66218881. The next prime is 66218897. The reversal of 66218890 is 9881266.

It can be written as a sum of positive squares in 4 ways, for example, as 57592921 + 8625969 = 7589^2 + 2937^2 .

It is not an unprimeable number, because it can be changed into a prime (66218897) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 113881 + ... + 114460.

Almost surely, 2^66218890 is an apocalyptic number.

66218890 is a deficient number, since it is larger than the sum of its proper divisors (57085790).

66218890 is a wasteful number, since it uses less digits than its factorization.

66218890 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 228377.

The product of its (nonzero) digits is 41472, while the sum is 40.

The square root of 66218890 is about 8137.4990015360. The cubic root of 66218890 is about 404.5702701989.

The spelling of 66218890 in words is "sixty-six million, two hundred eighteen thousand, eight hundred ninety".