21613240721017 has 16 divisors (see below), whose sum is σ = 23584985592192. Its totient is φ = 19642647611520.

The previous prime is 21613240720993. The next prime is 21613240721047. The reversal of 21613240721017 is 71012704231612.

It is a cyclic number.

It is not a de Polignac number, because 21613240721017 - 2⁷ = 21613240720889 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21613240721047) 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, 676306603 + ... + 676338559.

It is an arithmetic number, because the mean of its divisors is an integer number (1474061599512).

Almost surely, 2^{21613240721017} is an apocalyptic number.

It is an amenable number.

21613240721017 is a deficient number, since it is larger than the sum of its proper divisors (1971744871175).

21613240721017 is a wasteful number, since it uses less digits than its factorization.

21613240721017 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 48048.

The product of its (nonzero) digits is 28224, while the sum is 37.

Adding to 21613240721017 its reverse (71012704231612), we get a palindrome (92625944952629).

The spelling of 21613240721017 in words is "twenty-one trillion, six hundred thirteen billion, two hundred forty million, seven hundred twenty-one thousand, seventeen".