21055320240 has 80 divisors (see below), whose sum is σ = 65687352288. Its totient is φ = 5578979328.

The previous prime is 21055320137. The next prime is 21055320263. The reversal of 21055320240 is 4202355012.

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

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 21055320240.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 241717 + ... + 317076.

Almost surely, 2^21055320240 is an apocalyptic number.

21055320240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21055320240 is an abundant number, since it is smaller than the sum of its proper divisors (44632032048).

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

21055320240 is a wasteful number, since it uses less digits than its factorization.

21055320240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 558966 (or 558960 counting only the distinct ones).

The product of its (nonzero) digits is 2400, while the sum is 24.

Adding to 21055320240 its reverse (4202355012), we get a palindrome (25257675252).

The spelling of 21055320240 in words is "twenty-one billion, fifty-five million, three hundred twenty thousand, two hundred forty".