21079800 has 216 divisors, whose sum is σ = 82695600. Its totient is φ = 4798080.

The previous prime is 21079789. The next prime is 21079801. The reversal of 21079800 is 897012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21079801) by changing a digit.

It is a polite number, since it can be written in 53 ways as a sum of consecutive naturals, for example, 88081 + ... + 88319.

It is an arithmetic number, because the mean of its divisors is an integer number (382850).

Almost surely, 2^21079800 is an apocalyptic number.

21079800 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21079800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (41347800).

21079800 is an abundant number, since it is smaller than the sum of its proper divisors (61615800).

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

21079800 is a wasteful number, since it uses less digits than its factorization.

21079800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 275 (or 256 counting only the distinct ones).

The product of its (nonzero) digits is 1008, while the sum is 27.

The square root of 21079800 is about 4591.2743329058. The cubic root of 21079800 is about 276.2414396452.

The spelling of 21079800 in words is "twenty-one million, seventy-nine thousand, eight hundred".