21005598 has 16 divisors (see below), whose sum is σ = 42405120. Its totient is φ = 6936216.

The previous prime is 21005597. The next prime is 21005609. The reversal of 21005598 is 89550012.

It is a super-3 number, since 3×21005598³ (a number of 23 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21005597) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15718 + ... + 17001.

It is an arithmetic number, because the mean of its divisors is an integer number (2650320).

Almost surely, 2^21005598 is an apocalyptic number.

21005598 is an abundant number, since it is smaller than the sum of its proper divisors (21399522).

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

21005598 is a wasteful number, since it uses less digits than its factorization.

21005598 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32831.

The product of its (nonzero) digits is 3600, while the sum is 30.

The square root of 21005598 is about 4583.1864461311. The cubic root of 21005598 is about 275.9169304721.

The spelling of 21005598 in words is "twenty-one million, five thousand, five hundred ninety-eight".