21420242320 has 80 divisors (see below), whose sum is σ = 50419741680. Its totient is φ = 8462057472.

The previous prime is 21420242317. The next prime is 21420242341. The reversal of 21420242320 is 2324202412.

It can be written as a sum of positive squares in 8 ways, for example, as 1793353104 + 19626889216 = 42348^2 + 140096^2 .

It is a tau number, because it is divible by the number of its divisors (80).

It is a junction number, because it is equal to n+sod(n) for n = 21420242291 and 21420242300.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 12053272 + ... + 12055048.

It is an arithmetic number, because the mean of its divisors is an integer number (630246771).

Almost surely, 2^21420242320 is an apocalyptic number.

21420242320 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21420242320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25209870840).

21420242320 is an abundant number, since it is smaller than the sum of its proper divisors (28999499360).

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

21420242320 is a wasteful number, since it uses less digits than its factorization.

21420242320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3572 (or 3566 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 22.

Adding to 21420242320 its reverse (2324202412), we get a palindrome (23744444732).

The spelling of 21420242320 in words is "twenty-one billion, four hundred twenty million, two hundred forty-two thousand, three hundred twenty".