20405485821 has 32 divisors (see below), whose sum is σ = 31626547200. Its totient is φ = 11460876480.

The previous prime is 20405485757. The next prime is 20405485823. The reversal of 20405485821 is 12858450402.

It is a happy number.

It is not a de Polignac number, because 20405485821 - 2⁶ = 20405485757 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20405485821.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20405485823) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2069020 + ... + 2078858.

It is an arithmetic number, because the mean of its divisors is an integer number (988329600).

Almost surely, 2^20405485821 is an apocalyptic number.

20405485821 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

20405485821 is a deficient number, since it is larger than the sum of its proper divisors (11221061379).

20405485821 is a wasteful number, since it uses less digits than its factorization.

20405485821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11529.

The product of its (nonzero) digits is 102400, while the sum is 39.

The spelling of 20405485821 in words is "twenty billion, four hundred five million, four hundred eighty-five thousand, eight hundred twenty-one".