21031320020 has 24 divisors (see below), whose sum is σ = 46490287200. Its totient is φ = 7969763232.

The previous prime is 21031319977. The next prime is 21031320031. The reversal of 21031320020 is 2002313012.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21031319977 and 21031320004.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 27672410 + ... + 27673169.

It is an arithmetic number, because the mean of its divisors is an integer number (1937095300).

Almost surely, 2^21031320020 is an apocalyptic number.

21031320020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21031320020 is an abundant number, since it is smaller than the sum of its proper divisors (25458967180).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21031320020 is a wasteful number, since it uses less digits than its factorization.

21031320020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55345607 (or 55345605 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 14.

Adding to 21031320020 its reverse (2002313012), we get a palindrome (23033633032).

The spelling of 21031320020 in words is "twenty-one billion, thirty-one million, three hundred twenty thousand, twenty".