21002444306531 has 4 divisors (see below), whose sum is σ = 21206351532912. Its totient is φ = 20798537080152.

The previous prime is 21002444306507. The next prime is 21002444306563. The reversal of 21002444306531 is 13560344420012.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21002444306531 is a prime.

It is a super-2 number, since 2×21002444306531² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21002444306491 and 21002444306500.

It is not an unprimeable number, because it can be changed into a prime (21002444306581) 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, 101953613036 + ... + 101953613241.

It is an arithmetic number, because the mean of its divisors is an integer number (5301587883228).

Almost surely, 2^{21002444306531} is an apocalyptic number.

21002444306531 is a deficient number, since it is larger than the sum of its proper divisors (203907226381).

21002444306531 is a wasteful number, since it uses less digits than its factorization.

21002444306531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 203907226380.

The product of its (nonzero) digits is 69120, while the sum is 35.

Adding to 21002444306531 its reverse (13560344420012), we get a palindrome (34562788726543).

The spelling of 21002444306531 in words is "twenty-one trillion, two billion, four hundred forty-four million, three hundred six thousand, five hundred thirty-one".