20947280891 has 4 divisors (see below), whose sum is σ = 20947577112. Its totient is φ = 20946984672.

The previous prime is 20947280831. The next prime is 20947280897. The reversal of 20947280891 is 19808274902.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 20947280891 - 2²² = 20943086587 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20947280897) 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, 26876 + ... + 206438.

It is an arithmetic number, because the mean of its divisors is an integer number (5236894278).

Almost surely, 2^20947280891 is an apocalyptic number.

20947280891 is a deficient number, since it is larger than the sum of its proper divisors (296221).

20947280891 is a wasteful number, since it uses less digits than its factorization.

20947280891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 296220.

The product of its (nonzero) digits is 580608, while the sum is 50.

The spelling of 20947280891 in words is "twenty billion, nine hundred forty-seven million, two hundred eighty thousand, eight hundred ninety-one".