21111028 has 12 divisors (see below), whose sum is σ = 37056292. Its totient is φ = 10523520.

The previous prime is 21111007. The next prime is 21111029. The reversal of 21111028 is 82011112.

It can be written as a sum of positive squares in 2 ways, for example, as 15147664 + 5963364 = 3892^2 + 2442^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21111029) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6483 + ... + 9178.

Almost surely, 2^21111028 is an apocalyptic number.

It is an amenable number.

21111028 is a deficient number, since it is larger than the sum of its proper divisors (15945264).

21111028 is a wasteful number, since it uses less digits than its factorization.

21111028 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16002 (or 16000 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 16.

The square root of 21111028 is about 4594.6738730839. The cubic root of 21111028 is about 276.3777820421.

The spelling of 21111028 in words is "twenty-one million, one hundred eleven thousand, twenty-eight".