21945128 has 16 divisors (see below), whose sum is σ = 42936480. Its totient is φ = 10495408.

The previous prime is 21945101. The next prime is 21945137. The reversal of 21945128 is 82154912.

It is a junction number, because it is equal to n+sod(n) for n = 21945094 and 21945103.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 59450 + ... + 59817.

It is an arithmetic number, because the mean of its divisors is an integer number (2683530).

Almost surely, 2^21945128 is an apocalyptic number.

It is an amenable number.

21945128 is a deficient number, since it is larger than the sum of its proper divisors (20991352).

21945128 is a wasteful number, since it uses less digits than its factorization.

21945128 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 119296 (or 119292 counting only the distinct ones).

The product of its digits is 5760, while the sum is 32.

The square root of 21945128 is about 4684.5627330627. The cubic root of 21945128 is about 279.9707792636.

The spelling of 21945128 in words is "twenty-one million, nine hundred forty-five thousand, one hundred twenty-eight".