20666778 has 16 divisors (see below), whose sum is σ = 45091296. Its totient is φ = 6262640.

The previous prime is 20666759. The next prime is 20666783. The reversal of 20666778 is 87766602.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 156501 + ... + 156632.

It is an arithmetic number, because the mean of its divisors is an integer number (2818206).

Almost surely, 2^20666778 is an apocalyptic number.

20666778 is an abundant number, since it is smaller than the sum of its proper divisors (24424518).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20666778 is a wasteful number, since it uses less digits than its factorization.

20666778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 313149.

The product of its (nonzero) digits is 169344, while the sum is 42.

The square root of 20666778 is about 4546.0728106796. The cubic root of 20666778 is about 274.4253698065.

The spelling of 20666778 in words is "twenty million, six hundred sixty-six thousand, seven hundred seventy-eight".