21255331240 has 64 divisors (see below), whose sum is σ = 56185436160. Its totient is φ = 7134654720.

The previous prime is 21255331231. The next prime is 21255331241. The reversal of 21255331240 is 4213355212.

It is a super-2 number, since 2×21255331240² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21255331199 and 21255331208.

It is not an unprimeable number, because it can be changed into a prime (21255331241) 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 15 ways as a sum of consecutive naturals, for example, 1852264 + ... + 1863703.

It is an arithmetic number, because the mean of its divisors is an integer number (877897440).

Almost surely, 2^21255331240 is an apocalyptic number.

21255331240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21255331240 is an abundant number, since it is smaller than the sum of its proper divisors (34930104920).

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

21255331240 is a wasteful number, since it uses less digits than its factorization.

21255331240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3716002 (or 3715998 counting only the distinct ones).

The product of its (nonzero) digits is 7200, while the sum is 28.

Adding to 21255331240 its reverse (4213355212), we get a palindrome (25468686452).

The spelling of 21255331240 in words is "twenty-one billion, two hundred fifty-five million, three hundred thirty-one thousand, two hundred forty".