21156211716 has 96 divisors (see below), whose sum is σ = 52330924800. Its totient is φ = 6638776320.

The previous prime is 21156211691. The next prime is 21156211717. The reversal of 21156211716 is 61711265112.

It is not an unprimeable number, because it can be changed into a prime (21156211717) 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, 5623276 + ... + 5627036.

It is an arithmetic number, because the mean of its divisors is an integer number (545113800).

Almost surely, 2^21156211716 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21156211716, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26165462400).

21156211716 is an abundant number, since it is smaller than the sum of its proper divisors (31174713084).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21156211716 is a wasteful number, since it uses less digits than its factorization.

21156211716 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4109 (or 4107 counting only the distinct ones).

The product of its digits is 5040, while the sum is 33.

Adding to 21156211716 its reverse (61711265112), we get a palindrome (82867476828).

The spelling of 21156211716 in words is "twenty-one billion, one hundred fifty-six million, two hundred eleven thousand, seven hundred sixteen".