20666977 has 4 divisors (see below), whose sum is σ = 20687380. Its totient is φ = 20646576.

The previous prime is 20666963. The next prime is 20666999. The reversal of 20666977 is 77966602.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 15358561 + 5308416 = 3919^2 + 2304^2 .

It is a cyclic number.

It is not a de Polignac number, because 20666977 - 2¹¹ = 20664929 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20666077) by changing a digit.

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, 8598 + ... + 10735.

It is an arithmetic number, because the mean of its divisors is an integer number (5171845).

Almost surely, 2^20666977 is an apocalyptic number.

It is an amenable number.

20666977 is a deficient number, since it is larger than the sum of its proper divisors (20403).

20666977 is a wasteful number, since it uses less digits than its factorization.

20666977 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20402.

The product of its (nonzero) digits is 190512, while the sum is 43.

The square root of 20666977 is about 4546.0946976498. The cubic root of 20666977 is about 274.4262506159.

Adding to 20666977 its product of nonzero digits (190512), we get a square (20857489 = 4567²).

The spelling of 20666977 in words is "twenty million, six hundred sixty-six thousand, nine hundred seventy-seven".