21628308 has 48 divisors (see below), whose sum is σ = 57216320. Its totient is φ = 6303744.

The previous prime is 21628283. The next prime is 21628339. The reversal of 21628308 is 80382612.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 685 + ... + 6612.

Almost surely, 2^21628308 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21628308, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28608160).

21628308 is an abundant number, since it is smaller than the sum of its proper divisors (35588012).

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

21628308 is a wasteful number, since it uses less digits than its factorization.

21628308 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7336 (or 7334 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 30.

The square root of 21628308 is about 4650.6244741970. The cubic root of 21628308 is about 278.6169381082.

The spelling of 21628308 in words is "twenty-one million, six hundred twenty-eight thousand, three hundred eight".