21002431320 has 96 divisors (see below), whose sum is σ = 73508526000. Its totient is φ = 5169828096.

The previous prime is 21002431291. The next prime is 21002431339. The reversal of 21002431320 is 2313420012.

21002431320 is a `hidden beast` number, since 2 + 100 + 243 + 1 + 320 = 666.

It is a super-2 number, since 2×21002431320² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 21002431293 and 21002431302.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2239170 + ... + 2248529.

Almost surely, 2^21002431320 is an apocalyptic number.

21002431320 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21002431320 is an abundant number, since it is smaller than the sum of its proper divisors (52506094680).

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

21002431320 is a wasteful number, since it uses less digits than its factorization.

21002431320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4487729 (or 4487722 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 18.

Adding to 21002431320 its reverse (2313420012), we get a palindrome (23315851332).

The spelling of 21002431320 in words is "twenty-one billion, two million, four hundred thirty-one thousand, three hundred twenty".