21193884 has 72 divisors (see below), whose sum is σ = 55862352. Its totient is φ = 6769920.

The previous prime is 21193853. The next prime is 21193889. The reversal of 21193884 is 48839112.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21193889) 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, 122422 + ... + 122594.

It is an arithmetic number, because the mean of its divisors is an integer number (775866).

Almost surely, 2^21193884 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21193884, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27931176).

21193884 is an abundant number, since it is smaller than the sum of its proper divisors (34668468).

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

21193884 is a wasteful number, since it uses less digits than its factorization.

21193884 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 307 (or 302 counting only the distinct ones).

The product of its digits is 13824, while the sum is 36.

The square root of 21193884 is about 4603.6815702218. The cubic root of 21193884 is about 276.7388834238.

The spelling of 21193884 in words is "twenty-one million, one hundred ninety-three thousand, eight hundred eighty-four".