21020120320 has 72 divisors (see below), whose sum is σ = 51710677704. Its totient is φ = 8180785152.

The previous prime is 21020120243. The next prime is 21020120327. The reversal of 21020120320 is 2302102012.

It can be written as a sum of positive squares in 4 ways, for example, as 3663638784 + 17356481536 = 60528^2 + 131744^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21020120320.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21020120327) 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, 174559 + ... + 269278.

It is an arithmetic number, because the mean of its divisors is an integer number (718203857).

Almost surely, 2^21020120320 is an apocalyptic number.

21020120320 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21020120320 is an abundant number, since it is smaller than the sum of its proper divisors (30690557384).

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

21020120320 is an equidigital number, since it uses as much as digits as its factorization.

21020120320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 443895 (or 443881 counting only the distinct ones).

The product of its (nonzero) digits is 48, while the sum is 13.

Adding to 21020120320 its reverse (2302102012), we get a palindrome (23322222332).

The spelling of 21020120320 in words is "twenty-one billion, twenty million, one hundred twenty thousand, three hundred twenty".