66666890 has 8 divisors (see below), whose sum is σ = 120000420. Its totient is φ = 26666752.

The previous prime is 66666881. The next prime is 66666913. The reversal of 66666890 is 9866666.

66666890 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 58262689 + 8404201 = 7633^2 + 2899^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3333335 + ... + 3333354.

Almost surely, 2^66666890 is an apocalyptic number.

66666890 is a deficient number, since it is larger than the sum of its proper divisors (53333530).

66666890 is a wasteful number, since it uses less digits than its factorization.

66666890 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6666696.

The product of its (nonzero) digits is 559872, while the sum is 47.

The square root of 66666890 is about 8164.9794855835. The cubic root of 66666890 is about 405.4805858239.

The spelling of 66666890 in words is "sixty-six million, six hundred sixty-six thousand, eight hundred ninety".