21055878 has 48 divisors (see below), whose sum is σ = 47357856. Its totient is φ = 6756480.

The previous prime is 21055873. The next prime is 21055897. The reversal of 21055878 is 87855012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21055871) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 75876 + ... + 76152.

It is an arithmetic number, because the mean of its divisors is an integer number (986622).

Almost surely, 2^21055878 is an apocalyptic number.

21055878 is an abundant number, since it is smaller than the sum of its proper divisors (26301978).

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

21055878 is a wasteful number, since it uses less digits than its factorization.

21055878 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 429 (or 426 counting only the distinct ones).

The product of its (nonzero) digits is 22400, while the sum is 36.

The square root of 21055878 is about 4588.6684343064. The cubic root of 21055878 is about 276.1369043548.

The spelling of 21055878 in words is "twenty-one million, fifty-five thousand, eight hundred seventy-eight".