21948318 has 48 divisors (see below), whose sum is σ = 55625856. Its totient is φ = 6123600.

The previous prime is 21948317. The next prime is 21948319. The reversal of 21948318 is 81384912.

It is an interprime number because it is at equal distance from previous prime (21948317) and next prime (21948319).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21948313) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3393 + ... + 7443.

It is an arithmetic number, because the mean of its divisors is an integer number (1158872).

Almost surely, 2^21948318 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21948318, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27812928).

21948318 is an abundant number, since it is smaller than the sum of its proper divisors (33677538).

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

21948318 is a wasteful number, since it uses less digits than its factorization.

21948318 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4109 (or 4106 counting only the distinct ones).

The product of its digits is 13824, while the sum is 36.

The square root of 21948318 is about 4684.9032007076. The cubic root of 21948318 is about 279.9843443628.

The spelling of 21948318 in words is "twenty-one million, nine hundred forty-eight thousand, three hundred eighteen".