21170515217 has 4 divisors (see below), whose sum is σ = 22284752880. Its totient is φ = 20056277556.

The previous prime is 21170515211. The next prime is 21170515237. The reversal of 21170515217 is 71251507112.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21170515217 - 2⁶ = 21170515153 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21170515211) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 557118803 + ... + 557118840.

It is an arithmetic number, because the mean of its divisors is an integer number (5571188220).

Almost surely, 2^21170515217 is an apocalyptic number.

It is an amenable number.

21170515217 is a deficient number, since it is larger than the sum of its proper divisors (1114237663).

21170515217 is a wasteful number, since it uses less digits than its factorization.

21170515217 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1114237662.

The product of its (nonzero) digits is 4900, while the sum is 32.

The spelling of 21170515217 in words is "twenty-one billion, one hundred seventy million, five hundred fifteen thousand, two hundred seventeen".