21628845 has 72 divisors (see below), whose sum is σ = 46256184. Its totient is φ = 9289728.

The previous prime is 21628837. The next prime is 21628877. The reversal of 21628845 is 54882612.

21628845 is a `hidden beast` number, since 21 + 628 + 8 + 4 + 5 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 11573604 + 10055241 = 3402^2 + 3171^2 .

It is not a de Polignac number, because 21628845 - 2³ = 21628837 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 37197 + ... + 37773.

It is an arithmetic number, because the mean of its divisors is an integer number (642447).

Almost surely, 2^21628845 is an apocalyptic number.

It is an amenable number.

21628845 is an abundant number, since it is smaller than the sum of its proper divisors (24627339).

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

21628845 is a wasteful number, since it uses less digits than its factorization.

21628845 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 619 (or 609 counting only the distinct ones).

The product of its digits is 30720, while the sum is 36.

The square root of 21628845 is about 4650.6822080207. The cubic root of 21628845 is about 278.6192439760.

The spelling of 21628845 in words is "twenty-one million, six hundred twenty-eight thousand, eight hundred forty-five".