21735728 has 20 divisors (see below), whose sum is σ = 48129360. Its totient is φ = 9315264.

The previous prime is 21735719. The next prime is 21735737. The reversal of 21735728 is 82753712.

It is an interprime number because it is at equal distance from previous prime (21735719) and next prime (21735737).

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 in 3 ways as a sum of consecutive naturals, for example, 96923 + ... + 97146.

It is an arithmetic number, because the mean of its divisors is an integer number (2406468).

Almost surely, 2^21735728 is an apocalyptic number.

21735728 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21735728 is an abundant number, since it is smaller than the sum of its proper divisors (26393632).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21735728 is a wasteful number, since it uses less digits than its factorization.

21735728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 194084 (or 194078 counting only the distinct ones).

The product of its digits is 23520, while the sum is 35.

The square root of 21735728 is about 4662.1591564424. The cubic root of 21735728 is about 279.0774398244.

The spelling of 21735728 in words is "twenty-one million, seven hundred thirty-five thousand, seven hundred twenty-eight".