20666777 has 4 divisors (see below), whose sum is σ = 20681316. Its totient is φ = 20652240.

The previous prime is 20666759. The next prime is 20666783. The reversal of 20666777 is 77766602.

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 9803161 + 10863616 = 3131^2 + 3296^2 .

It is a cyclic number.

It is not a de Polignac number, because 20666777 - 2⁸ = 20666521 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 polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4874 + ... + 8067.

It is an arithmetic number, because the mean of its divisors is an integer number (5170329).

Almost surely, 2^20666777 is an apocalyptic number.

It is an amenable number.

20666777 is a deficient number, since it is larger than the sum of its proper divisors (14539).

20666777 is a wasteful number, since it uses less digits than its factorization.

20666777 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14538.

The product of its (nonzero) digits is 148176, while the sum is 41.

The square root of 20666777 is about 4546.0727006945. The cubic root of 20666777 is about 274.4253653803.

The spelling of 20666777 in words is "twenty million, six hundred sixty-six thousand, seven hundred seventy-seven".