21243232140 has 192 divisors, whose sum is σ = 65180976000. Its totient is φ = 5137883136.

The previous prime is 21243232139. The next prime is 21243232177. The reversal of 21243232140 is 4123234212.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 21243232140.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 19871526 + ... + 19872594.

It is an arithmetic number, because the mean of its divisors is an integer number (339484250).

Almost surely, 2^21243232140 is an apocalyptic number.

21243232140 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 21243232140, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32590488000).

21243232140 is an abundant number, since it is smaller than the sum of its proper divisors (43937743860).

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

21243232140 is a wasteful number, since it uses less digits than its factorization.

21243232140 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1516 (or 1514 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 24.

Adding to 21243232140 its reverse (4123234212), we get a palindrome (25366466352).

The spelling of 21243232140 in words is "twenty-one billion, two hundred forty-three million, two hundred thirty-two thousand, one hundred forty".