21013251017 has 16 divisors (see below), whose sum is σ = 23948144640. Its totient is φ = 18263974800.

The previous prime is 21013250987. The next prime is 21013251031. The reversal of 21013251017 is 71015231012.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21013251017 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21013250983 and 21013251001.

It is not an unprimeable number, because it can be changed into a prime (21013251037) 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, 342917 + ... + 399522.

It is an arithmetic number, because the mean of its divisors is an integer number (1496759040).

Almost surely, 2^21013251017 is an apocalyptic number.

It is an amenable number.

21013251017 is a deficient number, since it is larger than the sum of its proper divisors (2934893623).

21013251017 is a wasteful number, since it uses less digits than its factorization.

21013251017 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 742564.

The product of its (nonzero) digits is 420, while the sum is 23.

Adding to 21013251017 its reverse (71015231012), we get a palindrome (92028482029).

The spelling of 21013251017 in words is "twenty-one billion, thirteen million, two hundred fifty-one thousand, seventeen".