21009488 has 40 divisors (see below), whose sum is σ = 43651968. Its totient is φ = 9770112.

The previous prime is 21009449. The next prime is 21009491. The reversal of 21009488 is 88490012.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12845 + ... + 14387.

Almost surely, 2^21009488 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 21009488, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21825984).

21009488 is an abundant number, since it is smaller than the sum of its proper divisors (22642480).

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

21009488 is a wasteful number, since it uses less digits than its factorization.

21009488 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1611 (or 1605 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 32.

The square root of 21009488 is about 4583.6108037223. The cubic root of 21009488 is about 275.9339616560.

The spelling of 21009488 in words is "twenty-one million, nine thousand, four hundred eighty-eight".