20891686583 has 4 divisors (see below), whose sum is σ = 20893600440. Its totient is φ = 20889772728.

The previous prime is 20891686547. The next prime is 20891686589. The reversal of 20891686583 is 38568619802.

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

It is a cyclic number.

It is not a de Polignac number, because 20891686583 - 2¹⁰ = 20891685559 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 (20891686589) 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, 940460 + ... + 962417.

It is an arithmetic number, because the mean of its divisors is an integer number (5223400110).

Almost surely, 2^20891686583 is an apocalyptic number.

20891686583 is a deficient number, since it is larger than the sum of its proper divisors (1913857).

20891686583 is a wasteful number, since it uses less digits than its factorization.

20891686583 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1913856.

The product of its (nonzero) digits is 4976640, while the sum is 56.

The spelling of 20891686583 in words is "twenty billion, eight hundred ninety-one million, six hundred eighty-six thousand, five hundred eighty-three".