21801648 has 80 divisors (see below), whose sum is σ = 62067456. Its totient is φ = 6539520.

The previous prime is 21801641. The next prime is 21801653. The reversal of 21801648 is 84610812.

It is not an unprimeable number, because it can be changed into a prime (21801641) 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 15 ways as a sum of consecutive naturals, for example, 82765 + ... + 83027.

Almost surely, 2^21801648 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 21801648, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31033728).

21801648 is an abundant number, since it is smaller than the sum of its proper divisors (40265808).

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

21801648 is a wasteful number, since it uses less digits than its factorization.

21801648 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 442 (or 436 counting only the distinct ones).

The product of its (nonzero) digits is 3072, while the sum is 30.

The square root of 21801648 is about 4669.2234900463. The cubic root of 21801648 is about 279.3592832822.

It can be divided in two parts, 2180 and 1648, that added together give a triangular number (3828 = T₈₇).

The spelling of 21801648 in words is "twenty-one million, eight hundred one thousand, six hundred forty-eight".