21528816 has 40 divisors (see below), whose sum is σ = 55807440. Its totient is φ = 7151616.

The previous prime is 21528811. The next prime is 21528827. The reversal of 21528816 is 61882512.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21528811) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 18096 + ... + 19248.

It is an arithmetic number, because the mean of its divisors is an integer number (1395186).

Almost surely, 2^21528816 is an apocalyptic number.

It is an amenable number.

21528816 is an abundant number, since it is smaller than the sum of its proper divisors (34278624).

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

21528816 is a wasteful number, since it uses less digits than its factorization.

21528816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1553 (or 1547 counting only the distinct ones).

The product of its digits is 7680, while the sum is 33.

The square root of 21528816 is about 4639.9155164723. The cubic root of 21528816 is about 278.1890610505.

The spelling of 21528816 in words is "twenty-one million, five hundred twenty-eight thousand, eight hundred sixteen".