21117717389 has 4 divisors (see below), whose sum is σ = 21121400256. Its totient is φ = 21114034524.

The previous prime is 21117717349. The next prime is 21117717391. The reversal of 21117717389 is 98371771112.

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 21117717389 - 2³² = 16822750093 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21117717349) 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, 1832819 + ... + 1844304.

It is an arithmetic number, because the mean of its divisors is an integer number (5280350064).

Almost surely, 2^21117717389 is an apocalyptic number.

It is an amenable number.

21117717389 is a deficient number, since it is larger than the sum of its proper divisors (3682867).

21117717389 is an equidigital number, since it uses as much as digits as its factorization.

21117717389 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3682866.

The product of its digits is 148176, while the sum is 47.

The spelling of 21117717389 in words is "twenty-one billion, one hundred seventeen million, seven hundred seventeen thousand, three hundred eighty-nine".