20116661 has 4 divisors (see below), whose sum is σ = 21300012. Its totient is φ = 18933312.

The previous prime is 20116637. The next prime is 20116667. The reversal of 20116661 is 16661102.

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 18541636 + 1575025 = 4306^2 + 1255^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20116661 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20116667) 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, 591650 + ... + 591683.

It is an arithmetic number, because the mean of its divisors is an integer number (5325003).

Almost surely, 2^20116661 is an apocalyptic number.

It is an amenable number.

20116661 is a deficient number, since it is larger than the sum of its proper divisors (1183351).

20116661 is a wasteful number, since it uses less digits than its factorization.

20116661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1183350.

The product of its (nonzero) digits is 432, while the sum is 23.

The square root of 20116661 is about 4485.1600863291. The cubic root of 20116661 is about 271.9685165766.

Adding to 20116661 its reverse (16661102), we get a palindrome (36777763).

The spelling of 20116661 in words is "twenty million, one hundred sixteen thousand, six hundred sixty-one".