21544231013 has 4 divisors (see below), whose sum is σ = 21545613708. Its totient is φ = 21542848320.

The previous prime is 21544231001. The next prime is 21544231099. The reversal of 21544231013 is 31013244512.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 13953988129 + 7590242884 = 118127^2 + 87122^2 .

It is a cyclic number.

It is not a de Polignac number, because 21544231013 - 2⁴ = 21544230997 is a prime.

It is a super-2 number, since 2×21544231013² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21544230013) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 667706 + ... + 699227.

It is an arithmetic number, because the mean of its divisors is an integer number (5386403427).

Almost surely, 2^21544231013 is an apocalyptic number.

It is an amenable number.

21544231013 is a deficient number, since it is larger than the sum of its proper divisors (1382695).

21544231013 is a wasteful number, since it uses less digits than its factorization.

21544231013 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1382694.

The product of its (nonzero) digits is 2880, while the sum is 26.

Adding to 21544231013 its reverse (31013244512), we get a palindrome (52557475525).

The spelling of 21544231013 in words is "twenty-one billion, five hundred forty-four million, two hundred thirty-one thousand, thirteen".