21851648 has 120 divisors (see below), whose sum is σ = 55512072. Its totient is φ = 8515584.

The previous prime is 21851629. The next prime is 21851657. The reversal of 21851648 is 84615812.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 326111 + ... + 326177.

Almost surely, 2^21851648 is an apocalyptic number.

21851648 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 21851648, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27756036).

21851648 is an abundant number, since it is smaller than the sum of its proper divisors (33660424).

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

21851648 is an equidigital number, since it uses as much as digits as its factorization.

21851648 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 112 (or 89 counting only the distinct ones).

The product of its digits is 15360, while the sum is 35.

The square root of 21851648 is about 4674.5746330549. The cubic root of 21851648 is about 279.5726815184.

The spelling of 21851648 in words is "twenty-one million, eight hundred fifty-one thousand, six hundred forty-eight".