21020420320 has 48 divisors (see below), whose sum is σ = 51373193760. Its totient is φ = 8118229504.

The previous prime is 21020420303. The next prime is 21020420327. The reversal of 21020420320 is 2302402012.

It is a Harshad number since it is a multiple of its sum of digits (16).

It is a junction number, because it is equal to n+sod(n) for n = 21020420294 and 21020420303.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21020420327) 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, 2260492 + ... + 2269771.

It is an arithmetic number, because the mean of its divisors is an integer number (1070274870).

Almost surely, 2^21020420320 is an apocalyptic number.

21020420320 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21020420320 is an abundant number, since it is smaller than the sum of its proper divisors (30352773440).

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

21020420320 is a wasteful number, since it uses less digits than its factorization.

21020420320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4530307 (or 4530299 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 16.

Adding to 21020420320 its reverse (2302402012), we get a palindrome (23322822332).

The spelling of 21020420320 in words is "twenty-one billion, twenty million, four hundred twenty thousand, three hundred twenty".