20661513911 has 4 divisors (see below), whose sum is σ = 20747964000. Its totient is φ = 20575063824.

The previous prime is 20661513877. The next prime is 20661513947. The reversal of 20661513911 is 11931516602.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20661513911 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 (20661513011) 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, 43224686 + ... + 43225163.

It is an arithmetic number, because the mean of its divisors is an integer number (5186991000).

Almost surely, 2^20661513911 is an apocalyptic number.

20661513911 is a deficient number, since it is larger than the sum of its proper divisors (86450089).

20661513911 is an equidigital number, since it uses as much as digits as its factorization.

20661513911 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 86450088.

The product of its (nonzero) digits is 9720, while the sum is 35.

The spelling of 20661513911 in words is "twenty billion, six hundred sixty-one million, five hundred thirteen thousand, nine hundred eleven".