16671720016691 has 2 divisors, whose sum is σ = 16671720016692. Its totient is φ = 16671720016690.

The previous prime is 16671720016687. The next prime is 16671720016697. The reversal of 16671720016691 is 19661002717661.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 16671720016691 - 2² = 16671720016687 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (16671720016697) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8335860008345 + 8335860008346.

It is an arithmetic number, because the mean of its divisors is an integer number (8335860008346).

Almost surely, 2^{16671720016691} is an apocalyptic number.

16671720016691 is a deficient number, since it is larger than the sum of its proper divisors (1).

16671720016691 is an equidigital number, since it uses as much as digits as its factorization.

16671720016691 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1143072, while the sum is 53.

The spelling of 16671720016691 in words is "sixteen trillion, six hundred seventy-one billion, seven hundred twenty million, sixteen thousand, six hundred ninety-one".