21528945 has 12 divisors (see below), whose sum is σ = 37316916. Its totient is φ = 11482080.

The previous prime is 21528937. The next prime is 21529003. The reversal of 21528945 is 54982512.

It can be written as a sum of positive squares in 2 ways, for example, as 6036849 + 15492096 = 2457^2 + 3936^2 .

It is not a de Polignac number, because 21528945 - 2³ = 21528937 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 239166 + ... + 239255.

It is an arithmetic number, because the mean of its divisors is an integer number (3109743).

Almost surely, 2^21528945 is an apocalyptic number.

It is an amenable number.

21528945 is a deficient number, since it is larger than the sum of its proper divisors (15787971).

21528945 is a wasteful number, since it uses less digits than its factorization.

21528945 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 478432 (or 478429 counting only the distinct ones).

The product of its digits is 28800, while the sum is 36.

The square root of 21528945 is about 4639.9294175666. The cubic root of 21528945 is about 278.1896166828.

The spelling of 21528945 in words is "twenty-one million, five hundred twenty-eight thousand, nine hundred forty-five".