20051666 has 4 divisors (see below), whose sum is σ = 30077502. Its totient is φ = 10025832.

The previous prime is 20051663. The next prime is 20051677. The reversal of 20051666 is 66615002.

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

It can be written as a sum of positive squares in only one way, i.e., 18671041 + 1380625 = 4321^2 + 1175^2 .

It is not an unprimeable number, because it can be changed into a prime (20051663) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5012915 + ... + 5012918.

Almost surely, 2^20051666 is an apocalyptic number.

20051666 is a deficient number, since it is larger than the sum of its proper divisors (10025836).

20051666 is a wasteful number, since it uses less digits than its factorization.

20051666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10025835.

The product of its (nonzero) digits is 2160, while the sum is 26.

The square root of 20051666 is about 4477.9086636509. The cubic root of 20051666 is about 271.6752991766.

Adding to 20051666 its reverse (66615002), we get a palindrome (86666668).

The spelling of 20051666 in words is "twenty million, fifty-one thousand, six hundred sixty-six".