21431315520 has 336 divisors, whose sum is σ = 76854314160. Its totient is φ = 5474746368.

The previous prime is 21431315513. The next prime is 21431315561. The reversal of 21431315520 is 2551313412.

21431315520 is a `hidden beast` number, since 2 + 1 + 4 + 3 + 131 + 5 + 520 = 666.

It can be written as a sum of positive squares in 8 ways, for example, as 2194735104 + 19236580416 = 46848^2 + 138696^2 .

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 47 ways as a sum of consecutive naturals, for example, 11441304 + ... + 11443176.

Almost surely, 2^21431315520 is an apocalyptic number.

21431315520 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 21431315520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38427157080).

21431315520 is an abundant number, since it is smaller than the sum of its proper divisors (55422998640).

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

21431315520 is a wasteful number, since it uses less digits than its factorization.

21431315520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2062 (or 2049 counting only the distinct ones).

The product of its (nonzero) digits is 3600, while the sum is 27.

Adding to 21431315520 its reverse (2551313412), we get a palindrome (23982628932).

The spelling of 21431315520 in words is "twenty-one billion, four hundred thirty-one million, three hundred fifteen thousand, five hundred twenty".