20931780853 has 4 divisors (see below), whose sum is σ = 20933966560. Its totient is φ = 20929595148.

The previous prime is 20931780851. The next prime is 20931780911. The reversal of 20931780853 is 35808713902.

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 20931780853 - 2¹ = 20931780851 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 (20931780851) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1078425 + ... + 1097662.

It is an arithmetic number, because the mean of its divisors is an integer number (5233491640).

Almost surely, 2^20931780853 is an apocalyptic number.

It is an amenable number.

20931780853 is a deficient number, since it is larger than the sum of its proper divisors (2185707).

20931780853 is an equidigital number, since it uses as much as digits as its factorization.

20931780853 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2185706.

The product of its (nonzero) digits is 362880, while the sum is 46.

The spelling of 20931780853 in words is "twenty billion, nine hundred thirty-one million, seven hundred eighty thousand, eight hundred fifty-three".