21601748 has 36 divisors (see below), whose sum is σ = 44241120. Its totient is φ = 9202032.

The previous prime is 21601721. The next prime is 21601757. The reversal of 21601748 is 84710612.

It is a self number, because there is not a number n which added to its sum of digits gives 21601748.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 59993 + ... + 60351.

It is an arithmetic number, because the mean of its divisors is an integer number (1228920).

Almost surely, 2^21601748 is an apocalyptic number.

21601748 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21601748, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22120560).

21601748 is an abundant number, since it is smaller than the sum of its proper divisors (22639372).

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

21601748 is a wasteful number, since it uses less digits than its factorization.

21601748 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 684 (or 675 counting only the distinct ones).

The product of its (nonzero) digits is 2688, while the sum is 29.

The square root of 21601748 is about 4647.7680665025. The cubic root of 21601748 is about 278.5028423116.

The spelling of 21601748 in words is "twenty-one million, six hundred one thousand, seven hundred forty-eight".