21002101320 has 128 divisors (see below), whose sum is σ = 67522947840. Its totient is φ = 5212247040.

The previous prime is 21002101319. The next prime is 21002101349. The reversal of 21002101320 is 2310120012.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is a junction number, because it is equal to n+sod(n) for n = 21002101296 and 21002101305.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 711 + ... + 204950.

It is an arithmetic number, because the mean of its divisors is an integer number (527523030).

Almost surely, 2^21002101320 is an apocalyptic number.

21002101320 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 21002101320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33761473920).

21002101320 is an abundant number, since it is smaller than the sum of its proper divisors (46520846520).

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

21002101320 is a wasteful number, since it uses less digits than its factorization.

21002101320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 205735 (or 205731 counting only the distinct ones).

The product of its (nonzero) digits is 24, while the sum is 12.

Adding to 21002101320 its reverse (2310120012), we get a palindrome (23312221332).

The spelling of 21002101320 in words is "twenty-one billion, two million, one hundred one thousand, three hundred twenty".