21011345457217 has 4 divisors (see below), whose sum is σ = 21011523382980. Its totient is φ = 21011167531456.

The previous prime is 21011345457197. The next prime is 21011345457251. The reversal of 21011345457217 is 71275454311012.

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 16186452051121 + 4824893406096 = 4023239^2 + 2196564^2 .

It is a cyclic number.

It is not a de Polignac number, because 21011345457217 - 2²³ = 21011337068609 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21011345457317) 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, 88785628 + ... + 89021965.

It is an arithmetic number, because the mean of its divisors is an integer number (5252880845745).

Almost surely, 2^{21011345457217} is an apocalyptic number.

It is an amenable number.

21011345457217 is a deficient number, since it is larger than the sum of its proper divisors (177925763).

21011345457217 is a wasteful number, since it uses less digits than its factorization.

21011345457217 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 177925762.

The product of its (nonzero) digits is 235200, while the sum is 43.

Adding to 21011345457217 its reverse (71275454311012), we get a palindrome (92286799768229).

The spelling of 21011345457217 in words is "twenty-one trillion, eleven billion, three hundred forty-five million, four hundred fifty-seven thousand, two hundred seventeen".