21396241818 has 96 divisors (see below), whose sum is σ = 55469232000. Its totient is φ = 5831215488.

The previous prime is 21396241813. The next prime is 21396241897. The reversal of 21396241818 is 81814269312.

21396241818 is a `hidden beast` number, since 2 + 1 + 3 + 9 + 624 + 1 + 8 + 18 = 666.

It is not an unprimeable number, because it can be changed into a prime (21396241813) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 268008 + ... + 338556.

It is an arithmetic number, because the mean of its divisors is an integer number (577804500).

Almost surely, 2^21396241818 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21396241818, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27734616000).

21396241818 is an abundant number, since it is smaller than the sum of its proper divisors (34072990182).

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

21396241818 is a wasteful number, since it uses less digits than its factorization.

21396241818 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 70676 (or 70673 counting only the distinct ones).

The product of its digits is 165888, while the sum is 45.

The spelling of 21396241818 in words is "twenty-one billion, three hundred ninety-six million, two hundred forty-one thousand, eight hundred eighteen".