21128801 has 4 divisors (see below), whose sum is σ = 21158592. Its totient is φ = 21099012.

The previous prime is 21128797. The next prime is 21128843. The reversal of 21128801 is 10882112.

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 21128801 - 2² = 21128797 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21128851) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13805 + ... + 15258.

It is an arithmetic number, because the mean of its divisors is an integer number (5289648).

Almost surely, 2^21128801 is an apocalyptic number.

It is an amenable number.

21128801 is a deficient number, since it is larger than the sum of its proper divisors (29791).

21128801 is an equidigital number, since it uses as much as digits as its factorization.

21128801 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29790.

The product of its (nonzero) digits is 256, while the sum is 23.

The square root of 21128801 is about 4596.6075534028. The cubic root of 21128801 is about 276.4553194712.

The spelling of 21128801 in words is "twenty-one million, one hundred twenty-eight thousand, eight hundred one".