21785148 has 144 divisors (see below), whose sum is σ = 71285760. Its totient is φ = 5443200.

The previous prime is 21785131. The next prime is 21785149. The reversal of 21785148 is 84158712.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21785149) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 80253 + ... + 80523.

It is an arithmetic number, because the mean of its divisors is an integer number (495040).

Almost surely, 2^21785148 is an apocalyptic number.

21785148 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 21785148, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35642880).

21785148 is an abundant number, since it is smaller than the sum of its proper divisors (49500612).

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

21785148 is a wasteful number, since it uses less digits than its factorization.

21785148 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 328 (or 323 counting only the distinct ones).

The product of its digits is 17920, while the sum is 36.

The square root of 21785148 is about 4667.4562665332. The cubic root of 21785148 is about 279.2887902702.

The spelling of 21785148 in words is "twenty-one million, seven hundred eighty-five thousand, one hundred forty-eight".