21128998 has 32 divisors (see below), whose sum is σ = 36000288. Its totient is φ = 9216000.

The previous prime is 21128971. The next prime is 21129037. The reversal of 21128998 is 89982112.

It is a self number, because there is not a number n which added to its sum of digits gives 21128998.

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 an upside-down number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 82086 + ... + 82342.

It is an arithmetic number, because the mean of its divisors is an integer number (1125009).

Almost surely, 2^21128998 is an apocalyptic number.

21128998 is a deficient number, since it is larger than the sum of its proper divisors (14871290).

21128998 is a wasteful number, since it uses less digits than its factorization.

21128998 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 408.

The product of its digits is 20736, while the sum is 40.

The square root of 21128998 is about 4596.6289821999. The cubic root of 21128998 is about 276.4561786701.

The spelling of 21128998 in words is "twenty-one million, one hundred twenty-eight thousand, nine hundred ninety-eight".