18910691 has 2 divisors, whose sum is σ = 18910692. Its totient is φ = 18910690.

The previous prime is 18910687. The next prime is 18910693. The reversal of 18910691 is 19601981.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 18910691 - 2² = 18910687 is a prime.

It is a super-2 number, since 2×18910691² = 715228468194962, which contains 22 as substring.

Together with 18910693, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (18910693) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9455345 + 9455346.

It is an arithmetic number, because the mean of its divisors is an integer number (9455346).

Almost surely, 2^18910691 is an apocalyptic number.

18910691 is a deficient number, since it is larger than the sum of its proper divisors (1).

18910691 is an equidigital number, since it uses as much as digits as its factorization.

18910691 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3888, while the sum is 35.

The square root of 18910691 is about 4348.6424318401. The cubic root of 18910691 is about 266.4214163555.

The spelling of 18910691 in words is "eighteen million, nine hundred ten thousand, six hundred ninety-one".