16687691 has 2 divisors, whose sum is σ = 16687692. Its totient is φ = 16687690.

The previous prime is 16687669. The next prime is 16687717. The reversal of 16687691 is 19678661.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-16687691 is a prime.

It is a super-2 number, since 2×16687691² = 556958061822962, which contains 22 as substring.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (16687631) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8343845 + 8343846.

It is an arithmetic number, because the mean of its divisors is an integer number (8343846).

Almost surely, 2^16687691 is an apocalyptic number.

16687691 is a deficient number, since it is larger than the sum of its proper divisors (1).

16687691 is an equidigital number, since it uses as much as digits as its factorization.

16687691 is an evil number, because the sum of its binary digits is even.

The product of its digits is 108864, while the sum is 44.

The square root of 16687691 is about 4085.0570375455. The cubic root of 16687691 is about 255.5438399656.

The spelling of 16687691 in words is "sixteen million, six hundred eighty-seven thousand, six hundred ninety-one".