21032728 has 8 divisors (see below), whose sum is σ = 39436380. Its totient is φ = 10516360.

The previous prime is 21032699. The next prime is 21032731. The reversal of 21032728 is 82723012.

It is a tau number, because it is divible by the number of its divisors (8).

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 as a sum of consecutive naturals, namely, 1314538 + ... + 1314553.

Almost surely, 2^21032728 is an apocalyptic number.

It is an amenable number.

21032728 is a deficient number, since it is larger than the sum of its proper divisors (18403652).

21032728 is a wasteful number, since it uses less digits than its factorization.

21032728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2629097 (or 2629093 counting only the distinct ones).

The product of its (nonzero) digits is 1344, while the sum is 25.

The square root of 21032728 is about 4586.1452222973. The cubic root of 21032728 is about 276.0356671682.

The spelling of 21032728 in words is "twenty-one million, thirty-two thousand, seven hundred twenty-eight".