16670021 has 2 divisors, whose sum is σ = 16670022. Its totient is φ = 16670020.

The previous prime is 16669999. The next prime is 16670029. The reversal of 16670021 is 12007661.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14737921 + 1932100 = 3839^2 + 1390^2 .

It is a cyclic number.

It is not a de Polignac number, because 16670021 - 2⁶ = 16669957 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16670029) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8335010 + 8335011.

It is an arithmetic number, because the mean of its divisors is an integer number (8335011).

Almost surely, 2^16670021 is an apocalyptic number.

It is an amenable number.

16670021 is a deficient number, since it is larger than the sum of its proper divisors (1).

16670021 is an equidigital number, since it uses as much as digits as its factorization.

16670021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 504, while the sum is 23.

The square root of 16670021 is about 4082.8937042250. The cubic root of 16670021 is about 255.4536126968.

Adding to 16670021 its reverse (12007661), we get a palindrome (28677682).

The spelling of 16670021 in words is "sixteen million, six hundred seventy thousand, twenty-one".