21164242872 has 64 divisors (see below), whose sum is σ = 54933442560. Its totient is φ = 6787670400.

The previous prime is 21164242849. The next prime is 21164242873. The reversal of 21164242872 is 27824246112.

It is a hoax number, since the sum of its digits (39) coincides with the sum of the digits of its distinct prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 21164242872.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21164242873) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 46497 + ... + 210927.

It is an arithmetic number, because the mean of its divisors is an integer number (858335040).

Almost surely, 2^21164242872 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 21164242872, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27466721280).

21164242872 is an abundant number, since it is smaller than the sum of its proper divisors (33769199688).

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

21164242872 is a wasteful number, since it uses less digits than its factorization.

21164242872 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 164644 (or 164640 counting only the distinct ones).

The product of its digits is 86016, while the sum is 39.

Adding to 21164242872 its reverse (27824246112), we get a palindrome (48988488984).

The spelling of 21164242872 in words is "twenty-one billion, one hundred sixty-four million, two hundred forty-two thousand, eight hundred seventy-two".