21113002540 has 192 divisors, whose sum is σ = 55066152960. Its totient is φ = 6638837760.

The previous prime is 21113002517. The next prime is 21113002541. The reversal of 21113002540 is 4520031112.

It is a Harshad number since it is a multiple of its sum of digits (19).

It is not an unprimeable number, because it can be changed into a prime (21113002541) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 12126070 + ... + 12127810.

It is an arithmetic number, because the mean of its divisors is an integer number (286802880).

Almost surely, 2^21113002540 is an apocalyptic number.

21113002540 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 21113002540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27533076480).

21113002540 is an abundant number, since it is smaller than the sum of its proper divisors (33953150420).

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

21113002540 is a wasteful number, since it uses less digits than its factorization.

21113002540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1920 (or 1918 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 19.

Adding to 21113002540 its reverse (4520031112), we get a palindrome (25633033652).

The spelling of 21113002540 in words is "twenty-one billion, one hundred thirteen million, two thousand, five hundred forty".