20111650661 has 4 divisors (see below), whose sum is σ = 20133300300. Its totient is φ = 20090001024.

The previous prime is 20111650633. The next prime is 20111650673. The reversal of 20111650661 is 16605611102.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 16605611102 = 2 ⋅8302805551.

It can be written as a sum of positive squares in 2 ways, for example, as 4041017761 + 16070632900 = 63569^2 + 126770^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20111650661 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20111650631) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10823426 + ... + 10825283.

It is an arithmetic number, because the mean of its divisors is an integer number (5033325075).

Almost surely, 2^20111650661 is an apocalyptic number.

It is an amenable number.

20111650661 is a deficient number, since it is larger than the sum of its proper divisors (21649639).

20111650661 is an equidigital number, since it uses as much as digits as its factorization.

20111650661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21649638.

The product of its (nonzero) digits is 2160, while the sum is 29.

The spelling of 20111650661 in words is "twenty billion, one hundred eleven million, six hundred fifty thousand, six hundred sixty-one".