820884809781 has 32 divisors (see below), whose sum is σ = 1229954025600. Its totient is φ = 541035411840.

The previous prime is 820884809753. The next prime is 820884809783. The reversal of 820884809781 is 187908488028.

820884809781 is a `hidden beast` number, since 8 + 2 + 0 + 88 + 480 + 9 + 78 + 1 = 666.

It is not a de Polignac number, because 820884809781 - 2¹¹ = 820884807733 is a prime.

It is a super-2 number, since 2×820884809781² (a number of 25 digits) contains 22 as substring.

It is a Smith number, since the sum of its digits (63) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (820884809783) 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 31 ways as a sum of consecutive naturals, for example, 22716730 + ... + 22752836.

It is an arithmetic number, because the mean of its divisors is an integer number (38436063300).

Almost surely, 2^820884809781 is an apocalyptic number.

It is an amenable number.

820884809781 is a deficient number, since it is larger than the sum of its proper divisors (409069215819).

820884809781 is a wasteful number, since it uses less digits than its factorization.

820884809781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 45666 (or 45660 counting only the distinct ones).

The product of its (nonzero) digits is 16515072, while the sum is 63.

The spelling of 820884809781 in words is "eight hundred twenty billion, eight hundred eighty-four million, eight hundred nine thousand, seven hundred eighty-one".