21266028 has 36 divisors (see below), whose sum is σ = 61435920. Its totient is φ = 6075936.

The previous prime is 21266017. The next prime is 21266029. The reversal of 21266028 is 82066212.

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

It is a zygodrome in base 11.

It is a junction number, because it is equal to n+sod(n) for n = 21265992 and 21266010.

It is not an unprimeable number, because it can be changed into a prime (21266029) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 41943 + ... + 42446.

Almost surely, 2^21266028 is an apocalyptic number.

21266028 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21266028 is an abundant number, since it is smaller than the sum of its proper divisors (40169892).

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

21266028 is a wasteful number, since it uses less digits than its factorization.

21266028 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 84406 (or 84401 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 27.

The square root of 21266028 is about 4611.5103816429. The cubic root of 21266028 is about 277.0525342718.

The spelling of 21266028 in words is "twenty-one million, two hundred sixty-six thousand, twenty-eight".