21291305418 has 96 divisors (see below), whose sum is σ = 49274447040. Its totient is φ = 6625152000.

The previous prime is 21291305339. The next prime is 21291305443. The reversal of 21291305418 is 81450319212.

21291305418 is a `hidden beast` number, since 21 + 2 + 91 + 3 + 0 + 541 + 8 = 666.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 8325396 + ... + 8327952.

It is an arithmetic number, because the mean of its divisors is an integer number (513275490).

Almost surely, 2^21291305418 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21291305418, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24637223520).

21291305418 is an abundant number, since it is smaller than the sum of its proper divisors (27983141622).

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

21291305418 is a wasteful number, since it uses less digits than its factorization.

21291305418 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2932 (or 2929 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 36.

The spelling of 21291305418 in words is "twenty-one billion, two hundred ninety-one million, three hundred five thousand, four hundred eighteen".