21544042120 has 32 divisors (see below), whose sum is σ = 48903079320. Its totient is φ = 8541352960.

The previous prime is 21544042111. The next prime is 21544042139. The reversal of 21544042120 is 2124044512.

It can be written as a sum of positive squares in 4 ways, for example, as 9540210276 + 12003831844 = 97674^2 + 109562^2 .

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, 2378671 + ... + 2387710.

Almost surely, 2^21544042120 is an apocalyptic number.

21544042120 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21544042120 is an abundant number, since it is smaller than the sum of its proper divisors (27359037200).

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

21544042120 is a wasteful number, since it uses less digits than its factorization.

21544042120 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4766505 (or 4766501 counting only the distinct ones).

The product of its (nonzero) digits is 2560, while the sum is 25.

Adding to 21544042120 its reverse (2124044512), we get a palindrome (23668086632).

The spelling of 21544042120 in words is "twenty-one billion, five hundred forty-four million, forty-two thousand, one hundred twenty".