21644298 has 48 divisors (see below), whose sum is σ = 53483976. Its totient is φ = 6266880.

The previous prime is 21644267. The next prime is 21644303. The reversal of 21644298 is 89244612.

21644298 is a `hidden beast` number, since 2 + 1 + 644 + 2 + 9 + 8 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 19474569 + 2169729 = 4413^2 + 1473^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1258 + ... + 6698.

Almost surely, 2^21644298 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21644298, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26741988).

21644298 is an abundant number, since it is smaller than the sum of its proper divisors (31839678).

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

21644298 is a wasteful number, since it uses less digits than its factorization.

21644298 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5479 (or 5476 counting only the distinct ones).

The product of its digits is 27648, while the sum is 36.

The square root of 21644298 is about 4652.3432805415. The cubic root of 21644298 is about 278.6855825192.

The spelling of 21644298 in words is "twenty-one million, six hundred forty-four thousand, two hundred ninety-eight".