21001888 has 24 divisors (see below), whose sum is σ = 42311808. Its totient is φ = 10256064.

The previous prime is 21001879. The next prime is 21001889. The reversal of 21001888 is 88810012.

It is not an unprimeable number, because it can be changed into a prime (21001889) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6256 + ... + 9007.

It is an arithmetic number, because the mean of its divisors is an integer number (1762992).

Almost surely, 2^21001888 is an apocalyptic number.

It is an amenable number.

21001888 is an abundant number, since it is smaller than the sum of its proper divisors (21309920).

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

21001888 is a wasteful number, since it uses less digits than its factorization.

21001888 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15316 (or 15308 counting only the distinct ones).

The product of its (nonzero) digits is 1024, while the sum is 28.

The square root of 21001888 is about 4582.7816880144. The cubic root of 21001888 is about 275.9006854044.

The spelling of 21001888 in words is "twenty-one million, one thousand, eight hundred eighty-eight".