21049188 has 72 divisors (see below), whose sum is σ = 53510688. Its totient is φ = 6435072.

The previous prime is 21049177. The next prime is 21049199. The reversal of 21049188 is 88194012.

It is an interprime number because it is at equal distance from previous prime (21049177) and next prime (21049199).

It is an unprimeable number.

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, 186220 + ... + 186332.

It is an arithmetic number, because the mean of its divisors is an integer number (743204).

Almost surely, 2^21049188 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 21049188, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26755344).

21049188 is an abundant number, since it is smaller than the sum of its proper divisors (32461500).

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

21049188 is a wasteful number, since it uses less digits than its factorization.

21049188 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 201 (or 180 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 33.

The square root of 21049188 is about 4587.9394067490. The cubic root of 21049188 is about 276.1076559651.

The spelling of 21049188 in words is "twenty-one million, forty-nine thousand, one hundred eighty-eight".