21544220401 has 16 divisors (see below), whose sum is σ = 23910076800. Its totient is φ = 19246838400.

The previous prime is 21544220317. The next prime is 21544220417. The reversal of 21544220401 is 10402244512.

It is a cyclic number.

It is not a de Polignac number, because 21544220401 - 2³¹ = 19396736753 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21544220471) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 743340 + ... + 771778.

It is an arithmetic number, because the mean of its divisors is an integer number (1494379800).

Almost surely, 2^21544220401 is an apocalyptic number.

It is an amenable number.

21544220401 is a deficient number, since it is larger than the sum of its proper divisors (2365856399).

21544220401 is a wasteful number, since it uses less digits than its factorization.

21544220401 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29640.

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

Adding to 21544220401 its reverse (10402244512), we get a palindrome (31946464913).

The spelling of 21544220401 in words is "twenty-one billion, five hundred forty-four million, two hundred twenty thousand, four hundred one".