21078880 has 24 divisors (see below), whose sum is σ = 49799232. Its totient is φ = 8431488.

The previous prime is 21078877. The next prime is 21078919. The reversal of 21078880 is 8887012.

It is a Smith number, since the sum of its digits (34) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 65712 + ... + 66031.

It is an arithmetic number, because the mean of its divisors is an integer number (2074968).

Almost surely, 2^21078880 is an apocalyptic number.

21078880 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21078880 is an abundant number, since it is smaller than the sum of its proper divisors (28720352).

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

21078880 is a wasteful number, since it uses less digits than its factorization.

21078880 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 131758 (or 131750 counting only the distinct ones).

The product of its (nonzero) digits is 7168, while the sum is 34.

The square root of 21078880 is about 4591.1741417637. The cubic root of 21078880 is about 276.2374208559.

The spelling of 21078880 in words is "twenty-one million, seventy-eight thousand, eight hundred eighty".