21366198 has 48 divisors (see below), whose sum is σ = 53304576. Its totient is φ = 6058800.

The previous prime is 21366197. The next prime is 21366221. The reversal of 21366198 is 89166312.

21366198 is a `hidden beast` number, since 2 + 1 + 36 + 619 + 8 = 666.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21366197) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 18465 + ... + 19587.

It is an arithmetic number, because the mean of its divisors is an integer number (1110512).

Almost surely, 2^21366198 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21366198, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26652288).

21366198 is an abundant number, since it is smaller than the sum of its proper divisors (31938378).

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

21366198 is a wasteful number, since it uses less digits than its factorization.

21366198 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1289 (or 1286 counting only the distinct ones).

The product of its digits is 15552, while the sum is 36.

The square root of 21366198 is about 4622.3584889102. The cubic root of 21366198 is about 277.4868559637.

The spelling of 21366198 in words is "twenty-one million, three hundred sixty-six thousand, one hundred ninety-eight".