21128741 has 8 divisors (see below), whose sum is σ = 22332480. Its totient is φ = 19934208.

The previous prime is 21128719. The next prime is 21128747. The reversal of 21128741 is 14782112.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21128741 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21128741.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21128747) 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, 2720 + ... + 7046.

It is an arithmetic number, because the mean of its divisors is an integer number (2791560).

Almost surely, 2^21128741 is an apocalyptic number.

It is an amenable number.

21128741 is a deficient number, since it is larger than the sum of its proper divisors (1203739).

21128741 is a wasteful number, since it uses less digits than its factorization.

21128741 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4603.

The product of its digits is 896, while the sum is 26.

The square root of 21128741 is about 4596.6010268458. The cubic root of 21128741 is about 276.4550577852.

The spelling of 21128741 in words is "twenty-one million, one hundred twenty-eight thousand, seven hundred forty-one".