16779991 has 2 divisors, whose sum is σ = 16779992. Its totient is φ = 16779990.

The previous prime is 16779989. The next prime is 16780007. The reversal of 16779991 is 19997761.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 16779991 - 2¹ = 16779989 is a prime.

Together with 16779989, 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 (16779911) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8389995 + 8389996.

It is an arithmetic number, because the mean of its divisors is an integer number (8389996).

Almost surely, 2^16779991 is an apocalyptic number.

16779991 is a deficient number, since it is larger than the sum of its proper divisors (1).

16779991 is an equidigital number, since it uses as much as digits as its factorization.

16779991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 214326, while the sum is 49.

The square root of 16779991 is about 4096.3387311110. The cubic root of 16779991 is about 256.0141136018.

The spelling of 16779991 in words is "sixteen million, seven hundred seventy-nine thousand, nine hundred ninety-one".