21099589 has 4 divisors (see below), whose sum is σ = 24113824. Its totient is φ = 18085356.

The previous prime is 21099587. The next prime is 21099593. The reversal of 21099589 is 98599012.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21099589 - 2¹ = 21099587 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21099587) 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 3 ways as a sum of consecutive naturals, for example, 1507107 + ... + 1507120.

It is an arithmetic number, because the mean of its divisors is an integer number (6028456).

Almost surely, 2^21099589 is an apocalyptic number.

It is an amenable number.

21099589 is a deficient number, since it is larger than the sum of its proper divisors (3014235).

21099589 is an equidigital number, since it uses as much as digits as its factorization.

21099589 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3014234.

The product of its (nonzero) digits is 58320, while the sum is 43.

The square root of 21099589 is about 4593.4288935391. The cubic root of 21099589 is about 276.3278546355.

It can be divided in two parts, 210 and 99589, that added together give a palindrome (99799).

The spelling of 21099589 in words is "twenty-one million, ninety-nine thousand, five hundred eighty-nine".