21197800 has 96 divisors (see below), whose sum is σ = 54996480. Its totient is φ = 7545600.

The previous prime is 21197773. The next prime is 21197821. The reversal of 21197800 is 879112.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 80469 + ... + 80731.

It is an arithmetic number, because the mean of its divisors is an integer number (572880).

Almost surely, 2^21197800 is an apocalyptic number.

21197800 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 21197800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27498240).

21197800 is an abundant number, since it is smaller than the sum of its proper divisors (33798680).

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

21197800 is a wasteful number, since it uses less digits than its factorization.

21197800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 323 (or 314 counting only the distinct ones).

The product of its (nonzero) digits is 1008, while the sum is 28.

The square root of 21197800 is about 4604.1068623567. The cubic root of 21197800 is about 276.7559267483.

The spelling of 21197800 in words is "twenty-one million, one hundred ninety-seven thousand, eight hundred".