21500235555240 has 128 divisors (see below), whose sum is σ = 69585681191040. Its totient is φ = 5282965165056.

The previous prime is 21500235555157. The next prime is 21500235555263. The reversal of 21500235555240 is 4255553200512.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 11361687 + ... + 13118246.

It is an arithmetic number, because the mean of its divisors is an integer number (543638134305).

Almost surely, 2^{21500235555240} is an apocalyptic number.

21500235555240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21500235555240 is an abundant number, since it is smaller than the sum of its proper divisors (48085445635800).

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

21500235555240 is a wasteful number, since it uses less digits than its factorization.

21500235555240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24480523 (or 24480519 counting only the distinct ones).

The product of its (nonzero) digits is 300000, while the sum is 39.

Adding to 21500235555240 its reverse (4255553200512), we get a palindrome (25755788755752).

The spelling of 21500235555240 in words is "twenty-one trillion, five hundred billion, two hundred thirty-five million, five hundred fifty-five thousand, two hundred forty".