21157215008017 has 16 divisors (see below), whose sum is σ = 23309458807104. Its totient is φ = 19043120200000.

The previous prime is 21157215007967. The next prime is 21157215008089. The reversal of 21157215008017 is 71080051275112.

It is a cyclic number.

It is not a de Polignac number, because 21157215008017 - 2¹⁹ = 21157214483729 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21157215008317) 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, 137354838 + ... + 137508784.

It is an arithmetic number, because the mean of its divisors is an integer number (1456841175444).

Almost surely, 2^{21157215008017} is an apocalyptic number.

It is an amenable number.

21157215008017 is a deficient number, since it is larger than the sum of its proper divisors (2152243799087).

21157215008017 is a wasteful number, since it uses less digits than its factorization.

21157215008017 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 277760.

The product of its (nonzero) digits is 39200, while the sum is 40.

The spelling of 21157215008017 in words is "twenty-one trillion, one hundred fifty-seven billion, two hundred fifteen million, eight thousand, seventeen".