21178394973 has 32 divisors (see below), whose sum is σ = 33586560000. Its totient is φ = 13149100656.

The previous prime is 21178394911. The next prime is 21178394977. The reversal of 21178394973 is 37949387112.

21178394973 is a `hidden beast` number, since 2 + 117 + 8 + 39 + 497 + 3 = 666.

It is not a de Polignac number, because 21178394973 - 2¹⁰ = 21178393949 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21178394977) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 319593 + ... + 380126.

It is an arithmetic number, because the mean of its divisors is an integer number (1049580000).

Almost surely, 2^21178394973 is an apocalyptic number.

It is an amenable number.

21178394973 is a deficient number, since it is larger than the sum of its proper divisors (12408165027).

21178394973 is a wasteful number, since it uses less digits than its factorization.

21178394973 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 699806 (or 699800 counting only the distinct ones).

The product of its digits is 2286144, while the sum is 54.

The spelling of 21178394973 in words is "twenty-one billion, one hundred seventy-eight million, three hundred ninety-four thousand, nine hundred seventy-three".