21117311071 has 4 divisors (see below), whose sum is σ = 21120649792. Its totient is φ = 21113972352.

The previous prime is 21117311063. The next prime is 21117311081. The reversal of 21117311071 is 17011371112.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21117311071 - 2³ = 21117311063 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21117311021) 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, 1659855 + ... + 1672528.

It is an arithmetic number, because the mean of its divisors is an integer number (5280162448).

Almost surely, 2^21117311071 is an apocalyptic number.

21117311071 is a deficient number, since it is larger than the sum of its proper divisors (3338721).

21117311071 is an equidigital number, since it uses as much as digits as its factorization.

21117311071 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3338720.

The product of its (nonzero) digits is 294, while the sum is 25.

Adding to 21117311071 its reverse (17011371112), we get a palindrome (38128682183).

The spelling of 21117311071 in words is "twenty-one billion, one hundred seventeen million, three hundred eleven thousand, seventy-one".