21528668 has 12 divisors (see below), whose sum is σ = 43057392. Its totient is φ = 9226560.

The previous prime is 21528631. The next prime is 21528673. The reversal of 21528668 is 86682512.

21528668 is an admirable number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 384413 + ... + 384468.

It is an arithmetic number, because the mean of its divisors is an integer number (3588116).

Almost surely, 2^21528668 is an apocalyptic number.

21528668 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21528668 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

21528668 is a wasteful number, since it uses less digits than its factorization.

21528668 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 768892 (or 768890 counting only the distinct ones).

The product of its digits is 46080, while the sum is 38.

The square root of 21528668 is about 4639.8995678786. The cubic root of 21528668 is about 278.1884235781.

The spelling of 21528668 in words is "twenty-one million, five hundred twenty-eight thousand, six hundred sixty-eight".