21528308 has 12 divisors (see below), whose sum is σ = 38008740. Its totient is φ = 10668672.

The previous prime is 21528271. The next prime is 21528313. The reversal of 21528308 is 80382512.

It can be written as a sum of positive squares in 2 ways, for example, as 3055504 + 18472804 = 1748^2 + 4298^2 .

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, 23363 + ... + 24266.

It is an arithmetic number, because the mean of its divisors is an integer number (3167395).

Almost surely, 2^21528308 is an apocalyptic number.

It is an amenable number.

21528308 is a deficient number, since it is larger than the sum of its proper divisors (16480432).

21528308 is a wasteful number, since it uses less digits than its factorization.

21528308 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 47746 (or 47744 counting only the distinct ones).

The product of its (nonzero) digits is 3840, while the sum is 29.

The square root of 21528308 is about 4639.8607737733. The cubic root of 21528308 is about 278.1868729575.

The spelling of 21528308 in words is "twenty-one million, five hundred twenty-eight thousand, three hundred eight".