16646381 has 2 divisors, whose sum is σ = 16646382. Its totient is φ = 16646380.

The previous prime is 16646353. The next prime is 16646401. The reversal of 16646381 is 18364661.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15760900 + 885481 = 3970^2 + 941^2 .

It is a cyclic number.

It is not a de Polignac number, because 16646381 - 2⁶ = 16646317 is a prime.

It is a super-2 number, since 2×16646381² = 554204000794322, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16646341) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8323190 + 8323191.

It is an arithmetic number, because the mean of its divisors is an integer number (8323191).

Almost surely, 2^16646381 is an apocalyptic number.

It is an amenable number.

16646381 is a deficient number, since it is larger than the sum of its proper divisors (1).

16646381 is an equidigital number, since it uses as much as digits as its factorization.

16646381 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 20736, while the sum is 35.

The square root of 16646381 is about 4079.9976715680. The cubic root of 16646381 is about 255.3328014056.

The spelling of 16646381 in words is "sixteen million, six hundred forty-six thousand, three hundred eighty-one".