21540628 has 12 divisors (see below), whose sum is σ = 37834132. Its totient is φ = 10730880.

The previous prime is 21540611. The next prime is 21540637. The reversal of 21540628 is 82604512.

It can be written as a sum of positive squares in 2 ways, for example, as 4334724 + 17205904 = 2082^2 + 4148^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21540596 and 21540605.

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 in 3 ways as a sum of consecutive naturals, for example, 8613 + ... + 10828.

Almost surely, 2^21540628 is an apocalyptic number.

It is an amenable number.

21540628 is a deficient number, since it is larger than the sum of its proper divisors (16293504).

21540628 is a wasteful number, since it uses less digits than its factorization.

21540628 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19722 (or 19720 counting only the distinct ones).

The product of its (nonzero) digits is 3840, while the sum is 28.

The square root of 21540628 is about 4641.1882099307. The cubic root of 21540628 is about 278.2399288179.

The spelling of 21540628 in words is "twenty-one million, five hundred forty thousand, six hundred twenty-eight".