21040023241520 has 80 divisors (see below), whose sum is σ = 49273180793760. Its totient is φ = 8354920089600.

The previous prime is 21040023241469. The next prime is 21040023241537. The reversal of 21040023241520 is 2514232004012.

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

It is a self number, because there is not a number n which added to its sum of digits gives 21040023241520.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 200785940 + ... + 200890700.

It is an arithmetic number, because the mean of its divisors is an integer number (615914759922).

Almost surely, 2^{21040023241520} is an apocalyptic number.

21040023241520 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 21040023241520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24636590396880).

21040023241520 is an abundant number, since it is smaller than the sum of its proper divisors (28233157552240).

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

21040023241520 is a wasteful number, since it uses less digits than its factorization.

21040023241520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 122974 (or 122968 counting only the distinct ones).

The product of its (nonzero) digits is 3840, while the sum is 26.

Adding to 21040023241520 its reverse (2514232004012), we get a palindrome (23554255245532).

The spelling of 21040023241520 in words is "twenty-one trillion, forty billion, twenty-three million, two hundred forty-one thousand, five hundred twenty".