16331921 has 2 divisors, whose sum is σ = 16331922. Its totient is φ = 16331920.

The previous prime is 16331879. The next prime is 16331923. The reversal of 16331921 is 12913361.

16331921 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13424896 + 2907025 = 3664^2 + 1705^2 .

It is a cyclic number.

It is not a de Polignac number, because 16331921 - 2²² = 12137617 is a prime.

It is a Sophie Germain prime.

Together with 16331923, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (16331923) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8165960 + 8165961.

It is an arithmetic number, because the mean of its divisors is an integer number (8165961).

Almost surely, 2^16331921 is an apocalyptic number.

It is an amenable number.

16331921 is a deficient number, since it is larger than the sum of its proper divisors (1).

16331921 is an equidigital number, since it uses as much as digits as its factorization.

16331921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 972, while the sum is 26.

The square root of 16331921 is about 4041.2771496150. The cubic root of 16331921 is about 253.7147737587.

The spelling of 16331921 in words is "sixteen million, three hundred thirty-one thousand, nine hundred twenty-one".