21645148 has 48 divisors (see below), whose sum is σ = 47113920. Its totient is φ = 8487936.

The previous prime is 21645133. The next prime is 21645167. The reversal of 21645148 is 84154612.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 16998 + ... + 18226.

It is an arithmetic number, because the mean of its divisors is an integer number (981540).

Almost surely, 2^21645148 is an apocalyptic number.

21645148 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 21645148, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23556960).

21645148 is an abundant number, since it is smaller than the sum of its proper divisors (25468772).

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

21645148 is a wasteful number, since it uses less digits than its factorization.

21645148 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1294 (or 1292 counting only the distinct ones).

The product of its digits is 7680, while the sum is 31.

The square root of 21645148 is about 4652.4346314591. The cubic root of 21645148 is about 278.6892305877.

The spelling of 21645148 in words is "twenty-one million, six hundred forty-five thousand, one hundred forty-eight".