21000558 has 16 divisors (see below), whose sum is σ = 42069456. Its totient is φ = 6988800.

The previous prime is 21000557. The next prime is 21000563. The reversal of 21000558 is 85500012.

It is a super-3 number, since 3×21000558³ (a number of 23 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21000557) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1710 + ... + 6702.

It is an arithmetic number, because the mean of its divisors is an integer number (2629341).

Almost surely, 2^21000558 is an apocalyptic number.

21000558 is an abundant number, since it is smaller than the sum of its proper divisors (21068898).

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

21000558 is a wasteful number, since it uses less digits than its factorization.

21000558 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5699.

The product of its (nonzero) digits is 400, while the sum is 21.

The square root of 21000558 is about 4582.6365773428. The cubic root of 21000558 is about 275.8948612350.

The spelling of 21000558 in words is "twenty-one million, five hundred fifty-eight", and thus it is an aban number.