21004868394 has 24 divisors (see below), whose sum is σ = 45961151652. Its totient is φ = 6932299200.

The previous prime is 21004868393. The next prime is 21004868411. The reversal of 21004868394 is 49386840012.

It is a happy number.

21004868394 is a `hidden beast` number, since 2 + 1 + 0 + 0 + 486 + 83 + 94 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 20245590369 + 759278025 = 142287^2 + 27555^2 .

It is not an unprimeable number, because it can be changed into a prime (21004868393) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 5775099 + ... + 5778734.

Almost surely, 2^21004868394 is an apocalyptic number.

21004868394 is an abundant number, since it is smaller than the sum of its proper divisors (24956283258).

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

21004868394 is a wasteful number, since it uses less digits than its factorization.

21004868394 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11553942 (or 11553939 counting only the distinct ones).

The product of its (nonzero) digits is 331776, while the sum is 45.

The spelling of 21004868394 in words is "twenty-one billion, four million, eight hundred sixty-eight thousand, three hundred ninety-four".