21003538878 has 24 divisors (see below), whose sum is σ = 52008763248. Its totient is φ = 6001011072.

The previous prime is 21003538873. The next prime is 21003538901. The reversal of 21003538878 is 87883530012.

21003538878 is a `hidden beast` number, since 2 + 100 + 3 + 538 + 8 + 7 + 8 = 666.

It is a super-2 number, since 2×21003538878² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21003538873) 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 11 ways as a sum of consecutive naturals, for example, 83347251 + ... + 83347502.

It is an arithmetic number, because the mean of its divisors is an integer number (2167031802).

Almost surely, 2^21003538878 is an apocalyptic number.

21003538878 is an abundant number, since it is smaller than the sum of its proper divisors (31005224370).

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

21003538878 is a wasteful number, since it uses less digits than its factorization.

21003538878 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 166694768 (or 166694765 counting only the distinct ones).

The product of its (nonzero) digits is 322560, while the sum is 45.

The spelling of 21003538878 in words is "twenty-one billion, three million, five hundred thirty-eight thousand, eight hundred seventy-eight".