20540911781 has 8 divisors (see below), whose sum is σ = 22261882104. Its totient is φ = 18840070080.

The previous prime is 20540911777. The next prime is 20540911813. The reversal of 20540911781 is 18711904502.

It can be written as a sum of positive squares in 4 ways, for example, as 443313025 + 20097598756 = 21055^2 + 141766^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 20540911781 - 2² = 20540911777 is a prime.

It is a super-2 number, since 2×20540911781² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20540911751) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5030030 + ... + 5034111.

It is an arithmetic number, because the mean of its divisors is an integer number (2782735263).

Almost surely, 2^20540911781 is an apocalyptic number.

It is an amenable number.

20540911781 is a deficient number, since it is larger than the sum of its proper divisors (1720970323).

20540911781 is a wasteful number, since it uses less digits than its factorization.

20540911781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10064311.

The product of its (nonzero) digits is 20160, while the sum is 38.

The spelling of 20540911781 in words is "twenty billion, five hundred forty million, nine hundred eleven thousand, seven hundred eighty-one".