21711728 has 40 divisors (see below), whose sum is σ = 43300800. Its totient is φ = 10543104.

The previous prime is 21711727. The next prime is 21711731. The reversal of 21711728 is 82711712.

It is a self number, because there is not a number n which added to its sum of digits gives 21711728.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21711727) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 112400 + ... + 112592.

It is an arithmetic number, because the mean of its divisors is an integer number (1082520).

Almost surely, 2^21711728 is an apocalyptic number.

It is an amenable number.

21711728 is a deficient number, since it is larger than the sum of its proper divisors (21589072).

21711728 is a wasteful number, since it uses less digits than its factorization.

21711728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 369 (or 363 counting only the distinct ones).

The product of its digits is 1568, while the sum is 29.

The square root of 21711728 is about 4659.5845308353. The cubic root of 21711728 is about 278.9746854213.

The spelling of 21711728 in words is "twenty-one million, seven hundred eleven thousand, seven hundred twenty-eight".