20110661 has 4 divisors (see below), whose sum is σ = 20759424. Its totient is φ = 19461900.

The previous prime is 20110631. The next prime is 20110687. The reversal of 20110661 is 16601102.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 20110661 - 2¹⁰ = 20109637 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 (20110631) 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, 324335 + ... + 324396.

It is an arithmetic number, because the mean of its divisors is an integer number (5189856).

Almost surely, 2^20110661 is an apocalyptic number.

It is an amenable number.

20110661 is a deficient number, since it is larger than the sum of its proper divisors (648763).

20110661 is an equidigital number, since it uses as much as digits as its factorization.

20110661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 648762.

The product of its (nonzero) digits is 72, while the sum is 17.

The square root of 20110661 is about 4484.4911640007. The cubic root of 20110661 is about 271.9414747569.

Adding to 20110661 its reverse (16601102), we get a palindrome (36711763).

The spelling of 20110661 in words is "twenty million, one hundred ten thousand, six hundred sixty-one".