21493888 has 32 divisors (see below), whose sum is σ = 46117260. Its totient is φ = 9919488.

The previous prime is 21493873. The next prime is 21493889. The reversal of 21493888 is 88839412.

It can be written as a sum of positive squares in 2 ways, for example, as 20866624 + 627264 = 4568^2 + 792^2 .

It is a tau number, because it is divible by the number of its divisors (32).

It is not an unprimeable number, because it can be changed into a prime (21493889) 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 3 ways as a sum of consecutive naturals, for example, 4795 + ... + 8122.

Almost surely, 2^21493888 is an apocalyptic number.

It is an amenable number.

21493888 is an abundant number, since it is smaller than the sum of its proper divisors (24623372).

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

21493888 is a wasteful number, since it uses less digits than its factorization.

21493888 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12944 (or 12932 counting only the distinct ones).

The product of its digits is 110592, while the sum is 43.

The square root of 21493888 is about 4636.1501269911. The cubic root of 21493888 is about 278.0385364862.

The spelling of 21493888 in words is "twenty-one million, four hundred ninety-three thousand, eight hundred eighty-eight".