21128401 has 8 divisors (see below), whose sum is σ = 24361344. Its totient is φ = 17949120.

The previous prime is 21128381. The next prime is 21128411. The reversal of 21128401 is 10482112.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21128401 - 2²¹ = 19031249 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21128411) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12565 + ... + 14146.

It is an arithmetic number, because the mean of its divisors is an integer number (3045168).

Almost surely, 2^21128401 is an apocalyptic number.

It is an amenable number.

21128401 is a deficient number, since it is larger than the sum of its proper divisors (3232943).

21128401 is a wasteful number, since it uses less digits than its factorization.

21128401 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26831.

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

The square root of 21128401 is about 4596.5640428477. The cubic root of 21128401 is about 276.4535748884.

The spelling of 21128401 in words is "twenty-one million, one hundred twenty-eight thousand, four hundred one".