16317781 has 2 divisors, whose sum is σ = 16317782. Its totient is φ = 16317780.

The previous prime is 16317779. The next prime is 16317797. The reversal of 16317781 is 18771361.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12895281 + 3422500 = 3591^2 + 1850^2 .

It is a cyclic number.

It is not a de Polignac number, because 16317781 - 2¹ = 16317779 is a prime.

It is a super-2 number, since 2×16317781² = 532539953527922, which contains 22 as substring.

Together with 16317779, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16315781) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8158890 + 8158891.

It is an arithmetic number, because the mean of its divisors is an integer number (8158891).

Almost surely, 2^16317781 is an apocalyptic number.

It is an amenable number.

16317781 is a deficient number, since it is larger than the sum of its proper divisors (1).

16317781 is an equidigital number, since it uses as much as digits as its factorization.

16317781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7056, while the sum is 34.

The square root of 16317781 is about 4039.5273238338. The cubic root of 16317781 is about 253.6415314511.

The spelling of 16317781 in words is "sixteen million, three hundred seventeen thousand, seven hundred eighty-one".