21393648 has 120 divisors (see below), whose sum is σ = 63835200. Its totient is φ = 6676992.

The previous prime is 21393623. The next prime is 21393653. The reversal of 21393648 is 84639312.

21393648 is a `hidden beast` number, since 2 + 1 + 3 + 9 + 3 + 648 = 666.

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

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

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, 196218 + ... + 196326.

It is an arithmetic number, because the mean of its divisors is an integer number (531960).

Almost surely, 2^21393648 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 21393648, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31917600).

21393648 is an abundant number, since it is smaller than the sum of its proper divisors (42441552).

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

21393648 is a wasteful number, since it uses less digits than its factorization.

21393648 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 199 (or 190 counting only the distinct ones).

The product of its digits is 31104, while the sum is 36.

The square root of 21393648 is about 4625.3267992651. The cubic root of 21393648 is about 277.6056378915.

The spelling of 21393648 in words is "twenty-one million, three hundred ninety-three thousand, six hundred forty-eight".