21128141 has 4 divisors (see below), whose sum is σ = 21150012. Its totient is φ = 21106272.

The previous prime is 21128137. The next prime is 21128167. The reversal of 21128141 is 14182112.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 9424900 + 11703241 = 3070^2 + 3421^2 .

It is a cyclic number.

It is not a de Polignac number, because 21128141 - 2² = 21128137 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21128131) 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, 9416 + ... + 11441.

It is an arithmetic number, because the mean of its divisors is an integer number (5287503).

Almost surely, 2^21128141 is an apocalyptic number.

It is an amenable number.

21128141 is a deficient number, since it is larger than the sum of its proper divisors (21871).

21128141 is a wasteful number, since it uses less digits than its factorization.

21128141 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21870.

The product of its digits is 128, while the sum is 20.

The square root of 21128141 is about 4596.5357607659. The cubic root of 21128141 is about 276.4524408978.

The spelling of 21128141 in words is "twenty-one million, one hundred twenty-eight thousand, one hundred forty-one".