21265128 has 48 divisors (see below), whose sum is σ = 57863520. Its totient is φ = 7055136.

The previous prime is 21265093. The next prime is 21265129. The reversal of 21265128 is 82156212.

It is a happy number.

21265128 is a `hidden beast` number, since 2 + 1 + 2 + 651 + 2 + 8 = 666.

It is not an unprimeable number, because it can be changed into a prime (21265129) 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, 18375 + ... + 19497.

It is an arithmetic number, because the mean of its divisors is an integer number (1205490).

Almost surely, 2^21265128 is an apocalyptic number.

It is an amenable number.

21265128 is an abundant number, since it is smaller than the sum of its proper divisors (36598392).

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

21265128 is a wasteful number, since it uses less digits than its factorization.

21265128 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1398 (or 1391 counting only the distinct ones).

The product of its digits is 1920, while the sum is 27.

The square root of 21265128 is about 4611.4127986985. The cubic root of 21265128 is about 277.0486258347.

The spelling of 21265128 in words is "twenty-one million, two hundred sixty-five thousand, one hundred twenty-eight".