21089628 has 36 divisors (see below), whose sum is σ = 60926320. Its totient is φ = 6025536.

The previous prime is 21089623. The next prime is 21089659. The reversal of 21089628 is 82698012.

21089628 is a `hidden beast` number, since 21 + 0 + 8 + 9 + 628 = 666.

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 21089592 and 21089601.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21089623) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 41593 + ... + 42096.

Almost surely, 2^21089628 is an apocalyptic number.

21089628 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21089628 is an abundant number, since it is smaller than the sum of its proper divisors (39836692).

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

21089628 is a wasteful number, since it uses less digits than its factorization.

21089628 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 83706 (or 83701 counting only the distinct ones).

The product of its (nonzero) digits is 13824, while the sum is 36.

The square root of 21089628 is about 4592.3444992727. The cubic root of 21089628 is about 276.2843635037.

The spelling of 21089628 in words is "twenty-one million, eighty-nine thousand, six hundred twenty-eight".