20156666 has 16 divisors (see below), whose sum is σ = 31100328. Its totient is φ = 9792000.

The previous prime is 20156629. The next prime is 20156681. The reversal of 20156666 is 66665102.

It can be written as a sum of positive squares in 4 ways, for example, as 11868025 + 8288641 = 3445^2 + 2879^2 .

It is a Curzon number.

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 7 ways as a sum of consecutive naturals, for example, 32576 + ... + 33188.

Almost surely, 2^20156666 is an apocalyptic number.

20156666 is a deficient number, since it is larger than the sum of its proper divisors (10943662).

20156666 is a wasteful number, since it uses less digits than its factorization.

20156666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1057.

The product of its (nonzero) digits is 12960, while the sum is 32.

The square root of 20156666 is about 4489.6175783690. The cubic root of 20156666 is about 272.1486806079.

The spelling of 20156666 in words is "twenty million, one hundred fifty-six thousand, six hundred sixty-six".