21242558 has 16 divisors (see below), whose sum is σ = 33097680. Its totient is φ = 10213056.

The previous prime is 21242549. The next prime is 21242563. The reversal of 21242558 is 85524212.

It is a Harshad number since it is a multiple of its sum of digits (29).

It is a self number, because there is not a number n which added to its sum of digits gives 21242558.

It is a congruent number.

It is an unprimeable number.

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, 17210 + ... + 18402.

It is an arithmetic number, because the mean of its divisors is an integer number (2068605).

Almost surely, 2^21242558 is an apocalyptic number.

21242558 is a deficient number, since it is larger than the sum of its proper divisors (11855122).

21242558 is a wasteful number, since it uses less digits than its factorization.

21242558 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1531.

The product of its digits is 6400, while the sum is 29.

The square root of 21242558 is about 4608.9649597279. The cubic root of 21242558 is about 276.9505748375.

The spelling of 21242558 in words is "twenty-one million, two hundred forty-two thousand, five hundred fifty-eight".