16128821 has 2 divisors, whose sum is σ = 16128822. Its totient is φ = 16128820.

The previous prime is 16128799. The next prime is 16128841. The reversal of 16128821 is 12882161.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11764900 + 4363921 = 3430^2 + 2089^2 .

It is an emirp because it is prime and its reverse (12882161) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 16128821 - 2⁶ = 16128757 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16128841) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8064410 + 8064411.

It is an arithmetic number, because the mean of its divisors is an integer number (8064411).

Almost surely, 2^16128821 is an apocalyptic number.

It is an amenable number.

16128821 is a deficient number, since it is larger than the sum of its proper divisors (1).

16128821 is an equidigital number, since it uses as much as digits as its factorization.

16128821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1536, while the sum is 29.

The square root of 16128821 is about 4016.0703430094. The cubic root of 16128821 is about 252.6586709790.

It can be divided in two parts, 161 and 28821, that added together give a palindrome (28982).

The spelling of 16128821 in words is "sixteen million, one hundred twenty-eight thousand, eight hundred twenty-one".