21368448 has 112 divisors (see below), whose sum is σ = 64104450. Its totient is φ = 7091712.

The previous prime is 21368429. The next prime is 21368453. The reversal of 21368448 is 84486312.

It can be written as a sum of positive squares in only one way, i.e., 13483584 + 7884864 = 3672^2 + 2808^2 .

It is a super-2 number, since 2×21368448² = 913221139857408, which contains 22 as substring.

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

It is a nude number because it is divisible by every one of its digits.

It is an unprimeable number.

It is a polite number, since it can be written in 13 ways as a sum of consecutive naturals, for example, 93198 + ... + 93426.

Almost surely, 2^21368448 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21368448, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32052225).

21368448 is an abundant number, since it is smaller than the sum of its proper divisors (42736002).

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

21368448 is an frugal number, since it uses more digits than its factorization.

21368448 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 261 (or 234 counting only the distinct ones).

The product of its digits is 36864, while the sum is 36.

The square root of 21368448 is about 4622.6018647511. The cubic root of 21368448 is about 277.4965960138.

The spelling of 21368448 in words is "twenty-one million, three hundred sixty-eight thousand, four hundred forty-eight".