21240442140 has 24 divisors (see below), whose sum is σ = 59473238160. Its totient is φ = 5664117888.

The previous prime is 21240442099. The next prime is 21240442151. The reversal of 21240442140 is 4124404212.

It is a self number, because there is not a number n which added to its sum of digits gives 21240442140.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 177003625 + ... + 177003744.

It is an arithmetic number, because the mean of its divisors is an integer number (2478051590).

Almost surely, 2^21240442140 is an apocalyptic number.

21240442140 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21240442140 is an abundant number, since it is smaller than the sum of its proper divisors (38232796020).

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

21240442140 is a wasteful number, since it uses less digits than its factorization.

21240442140 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 354007381 (or 354007379 counting only the distinct ones).

The product of its (nonzero) digits is 2048, while the sum is 24.

Adding to 21240442140 its reverse (4124404212), we get a palindrome (25364846352).

The spelling of 21240442140 in words is "twenty-one billion, two hundred forty million, four hundred forty-two thousand, one hundred forty".