21594728 has 8 divisors (see below), whose sum is σ = 40490130. Its totient is φ = 10797360.

The previous prime is 21594707. The next prime is 21594731. The reversal of 21594728 is 82749512.

It can be written as a sum of positive squares in only one way, i.e., 19695844 + 1898884 = 4438^2 + 1378^2 .

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

It is a junction number, because it is equal to n+sod(n) for n = 21594691 and 21594700.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1349663 + ... + 1349678.

Almost surely, 2^21594728 is an apocalyptic number.

It is an amenable number.

21594728 is a deficient number, since it is larger than the sum of its proper divisors (18895402).

21594728 is a wasteful number, since it uses less digits than its factorization.

21594728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2699347 (or 2699343 counting only the distinct ones).

The product of its digits is 40320, while the sum is 38.

The square root of 21594728 is about 4647.0128039419. The cubic root of 21594728 is about 278.4726703432.

It can be divided in two parts, 21594 and 728, that added together give a palindrome (22322).

The spelling of 21594728 in words is "twenty-one million, five hundred ninety-four thousand, seven hundred twenty-eight".