21016731717 has 32 divisors (see below), whose sum is σ = 31791801600. Its totient is φ = 13719062016.

The previous prime is 21016731713. The next prime is 21016731727. The reversal of 21016731717 is 71713761012.

It is not a de Polignac number, because 21016731717 - 2² = 21016731713 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21016731713) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 205053 + ... + 289965.

It is an arithmetic number, because the mean of its divisors is an integer number (993493800).

Almost surely, 2^21016731717 is an apocalyptic number.

21016731717 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

It is an amenable number.

21016731717 is a deficient number, since it is larger than the sum of its proper divisors (10775069883).

21016731717 is a wasteful number, since it uses less digits than its factorization.

21016731717 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 85114 (or 85108 counting only the distinct ones).

The product of its (nonzero) digits is 12348, while the sum is 36.

The spelling of 21016731717 in words is "twenty-one billion, sixteen million, seven hundred thirty-one thousand, seven hundred seventeen".