21598720 has 160 divisors (see below), whose sum is σ = 61871040. Its totient is φ = 7127040.

The previous prime is 21598673. The next prime is 21598727. The reversal of 21598720 is 2789512.

It is a tau number, because it is divible by the number of its divisors (160).

It is not an unprimeable number, because it can be changed into a prime (21598727) 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 15 ways as a sum of consecutive naturals, for example, 366051 + ... + 366109.

It is an arithmetic number, because the mean of its divisors is an integer number (386694).

Almost surely, 2^21598720 is an apocalyptic number.

21598720 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 21598720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30935520).

21598720 is an abundant number, since it is smaller than the sum of its proper divisors (40272320).

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

21598720 is a wasteful number, since it uses less digits than its factorization.

21598720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 106 (or 90 counting only the distinct ones).

The product of its (nonzero) digits is 10080, while the sum is 34.

The square root of 21598720 is about 4647.4423073342. The cubic root of 21598720 is about 278.4898287658.

The spelling of 21598720 in words is "twenty-one million, five hundred ninety-eight thousand, seven hundred twenty".