21002031320 has 64 divisors (see below), whose sum is σ = 47921544000. Its totient is φ = 8282779648.

The previous prime is 21002031317. The next prime is 21002031359. The reversal of 21002031320 is 2313020012.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21002031295 and 21002031304.

It is a congruent number.

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, 1269824 + ... + 1286256.

It is an arithmetic number, because the mean of its divisors is an integer number (748774125).

Almost surely, 2^21002031320 is an apocalyptic number.

21002031320 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 21002031320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23960772000).

21002031320 is an abundant number, since it is smaller than the sum of its proper divisors (26919512680).

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

21002031320 is a wasteful number, since it uses less digits than its factorization.

21002031320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16892 (or 16888 counting only the distinct ones).

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

Adding to 21002031320 its reverse (2313020012), we get a palindrome (23315051332).

The spelling of 21002031320 in words is "twenty-one billion, two million, thirty-one thousand, three hundred twenty".