21948864 has 84 divisors (see below), whose sum is σ = 67583304. Its totient is φ = 6268416.

The previous prime is 21948863. The next prime is 21948893. The reversal of 21948864 is 46884912.

It is a tau number, because it is divible by the number of its divisors (84).

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21948863) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 8242 + ... + 10574.

Almost surely, 2^21948864 is an apocalyptic number.

21948864 is a gapful number since it is divisible by the number (24) 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 21948864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33791652).

21948864 is an abundant number, since it is smaller than the sum of its proper divisors (45634440).

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

21948864 is a wasteful number, since it uses less digits than its factorization.

21948864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2362 (or 2345 counting only the distinct ones).

The product of its digits is 110592, while the sum is 42.

The square root of 21948864 is about 4684.9614726271. The cubic root of 21948864 is about 279.9866660317.

The spelling of 21948864 in words is "twenty-one million, nine hundred forty-eight thousand, eight hundred sixty-four".