20501822781 has 12 divisors (see below), whose sum is σ = 32305902720. Its totient is φ = 12425347080.

The previous prime is 20501822767. The next prime is 20501822827. The reversal of 20501822781 is 18722810502.

20501822781 is a `hidden beast` number, since 2 + 0 + 501 + 82 + 2 + 78 + 1 = 666.

It is not a de Polignac number, because 20501822781 - 2⁹ = 20501822269 is a prime.

It is a super-2 number, since 2×20501822781² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20501822881) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 103544461 + ... + 103544658.

It is an arithmetic number, because the mean of its divisors is an integer number (2692158560).

Almost surely, 2^20501822781 is an apocalyptic number.

It is an amenable number.

20501822781 is a deficient number, since it is larger than the sum of its proper divisors (11804079939).

20501822781 is a wasteful number, since it uses less digits than its factorization.

20501822781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 207089136 (or 207089133 counting only the distinct ones).

The product of its (nonzero) digits is 17920, while the sum is 36.

The spelling of 20501822781 in words is "twenty billion, five hundred one million, eight hundred twenty-two thousand, seven hundred eighty-one".