21090558 has 16 divisors (see below), whose sum is σ = 42233616. Its totient is φ = 7021440.

The previous prime is 21090547. The next prime is 21090583. The reversal of 21090558 is 85509012.

It is a super-3 number, since 3×21090558³ (a number of 23 digits) contains 333 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4710 + ... + 8022.

It is an arithmetic number, because the mean of its divisors is an integer number (2639601).

Almost surely, 2^21090558 is an apocalyptic number.

21090558 is an abundant number, since it is smaller than the sum of its proper divisors (21143058).

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

21090558 is a wasteful number, since it uses less digits than its factorization.

21090558 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4379.

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

The square root of 21090558 is about 4592.4457536263. The cubic root of 21090558 is about 276.2884245945.

The spelling of 21090558 in words is "twenty-one million, ninety thousand, five hundred fifty-eight".