21398560 has 48 divisors (see below), whose sum is σ = 53222400. Its totient is φ = 8107776.

The previous prime is 21398557. The next prime is 21398561. The reversal of 21398560 is 6589312.

It is not an unprimeable number, because it can be changed into a prime (21398561) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 480 + ... + 6559.

It is an arithmetic number, because the mean of its divisors is an integer number (1108800).

Almost surely, 2^21398560 is an apocalyptic number.

21398560 is a gapful number since it is divisible by the number (20) 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 21398560, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26611200).

21398560 is an abundant number, since it is smaller than the sum of its proper divisors (31823840).

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

21398560 is a wasteful number, since it uses less digits than its factorization.

21398560 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7073 (or 7065 counting only the distinct ones).

The product of its (nonzero) digits is 12960, while the sum is 34.

The square root of 21398560 is about 4625.8577582974. The cubic root of 21398560 is about 277.6268824302.

The spelling of 21398560 in words is "twenty-one million, three hundred ninety-eight thousand, five hundred sixty".