221281128 has 24 divisors (see below), whose sum is σ = 599303250. Its totient is φ = 73760352.

The previous prime is 221281121. The next prime is 221281147. The reversal of 221281128 is 821182122.

221281128 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 189943524 + 31337604 = 13782^2 + 5598^2 .

It is a tau number, because it is divible by the number of its divisors (24).

It is a nude number because it is divisible by every one of its digits.

It is not an unprimeable number, because it can be changed into a prime (221281121) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1536603 + ... + 1536746.

Almost surely, 2^221281128 is an apocalyptic number.

It is an amenable number.

221281128 is an abundant number, since it is smaller than the sum of its proper divisors (378022122).

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

221281128 is a wasteful number, since it uses less digits than its factorization.

221281128 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3073361 (or 3073354 counting only the distinct ones).

The product of its digits is 1024, while the sum is 27.

The square root of 221281128 is about 14875.5211001161. The cubic root of 221281128 is about 604.8506135731.

The spelling of 221281128 in words is "two hundred twenty-one million, two hundred eighty-one thousand, one hundred twenty-eight".