21028444 has 6 divisors (see below), whose sum is σ = 36799784. Its totient is φ = 10514220.

The previous prime is 21028433. The next prime is 21028477. The reversal of 21028444 is 44482012.

It is a super-2 number, since 2×21028444² = 884390914122272, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2628552 + ... + 2628559.

Almost surely, 2^21028444 is an apocalyptic number.

It is an amenable number.

21028444 is a deficient number, since it is larger than the sum of its proper divisors (15771340).

21028444 is a wasteful number, since it uses less digits than its factorization.

21028444 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5257115 (or 5257113 counting only the distinct ones).

The product of its (nonzero) digits is 2048, while the sum is 25.

The square root of 21028444 is about 4585.6781395994. The cubic root of 21028444 is about 276.0169246780.

The spelling of 21028444 in words is "twenty-one million, twenty-eight thousand, four hundred forty-four".