21297528 has 48 divisors (see below), whose sum is σ = 65922480. Its totient is φ = 6084864.

The previous prime is 21297509. The next prime is 21297539. The reversal of 21297528 is 82579212.

21297528 is a `hidden beast` number, since 2 + 129 + 7 + 528 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 21297492 and 21297501.

It is a congruent number.

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 11 ways as a sum of consecutive naturals, for example, 20625 + ... + 21632.

It is an arithmetic number, because the mean of its divisors is an integer number (1373385).

Almost surely, 2^21297528 is an apocalyptic number.

21297528 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21297528 is an abundant number, since it is smaller than the sum of its proper divisors (44624952).

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

21297528 is a wasteful number, since it uses less digits than its factorization.

21297528 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42276 (or 42269 counting only the distinct ones).

The product of its digits is 20160, while the sum is 36.

The square root of 21297528 is about 4614.9244847560. The cubic root of 21297528 is about 277.1892601550.

The spelling of 21297528 in words is "twenty-one million, two hundred ninety-seven thousand, five hundred twenty-eight".