21506201351617 has 16 divisors (see below), whose sum is σ = 22518430842240. Its totient is φ = 20500500064000.

The previous prime is 21506201351543. The next prime is 21506201351641. The reversal of 21506201351617 is 71615310260512.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21506201351617 - 2¹¹ = 21506201349569 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21506201351617.

It is not an unprimeable number, because it can be changed into a prime (21506201351017) 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, 8686734 + ... + 10884472.

It is an arithmetic number, because the mean of its divisors is an integer number (1407401927640).

Almost surely, 2^{21506201351617} is an apocalyptic number.

It is an amenable number.

21506201351617 is a deficient number, since it is larger than the sum of its proper divisors (1012229490623).

21506201351617 is a wasteful number, since it uses less digits than its factorization.

21506201351617 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2199224.

The product of its (nonzero) digits is 75600, while the sum is 40.

The spelling of 21506201351617 in words is "twenty-one trillion, five hundred six billion, two hundred one million, three hundred fifty-one thousand, six hundred seventeen".