21128041 has 4 divisors (see below), whose sum is σ = 23048784. Its totient is φ = 19207300.

The previous prime is 21128033. The next prime is 21128069. The reversal of 21128041 is 14082112.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21128041 - 2³ = 21128033 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21128441) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 960355 + ... + 960376.

It is an arithmetic number, because the mean of its divisors is an integer number (5762196).

Almost surely, 2^21128041 is an apocalyptic number.

It is an amenable number.

21128041 is a deficient number, since it is larger than the sum of its proper divisors (1920743).

21128041 is a wasteful number, since it uses less digits than its factorization.

21128041 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1920742.

The product of its (nonzero) digits is 128, while the sum is 19.

The square root of 21128041 is about 4596.5248829958. The cubic root of 21128041 is about 276.4520047451.

It can be divided in two parts, 2112 and 8041, that added together give a triangular number (10153 = T₁₄₂).

The spelling of 21128041 in words is "twenty-one million, one hundred twenty-eight thousand, forty-one".