21789800 has 24 divisors (see below), whose sum is σ = 50661750. Its totient is φ = 8715840.

The previous prime is 21789797. The next prime is 21789839. The reversal of 21789800 is 898712.

It is a happy number.

It can be written as a sum of positive squares in 3 ways, for example, as 21215236 + 574564 = 4606^2 + 758^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 54275 + ... + 54674.

Almost surely, 2^21789800 is an apocalyptic number.

21789800 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21789800 is an abundant number, since it is smaller than the sum of its proper divisors (28871950).

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

21789800 is a wasteful number, since it uses less digits than its factorization.

21789800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 108965 (or 108956 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 35.

The square root of 21789800 is about 4667.9545841835. The cubic root of 21789800 is about 279.3086686293.

It can be divided in two parts, 2178 and 9800, that multiplied together give a square (21344400 = 4620²).

The spelling of 21789800 in words is "twenty-one million, seven hundred eighty-nine thousand, eight hundred".