18957691 has 2 divisors, whose sum is σ = 18957692. Its totient is φ = 18957690.

The previous prime is 18957689. The next prime is 18957707. The reversal of 18957691 is 19675981.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 18957691 - 2¹ = 18957689 is a prime.

Together with 18957689, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (18957661) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9478845 + 9478846.

It is an arithmetic number, because the mean of its divisors is an integer number (9478846).

Almost surely, 2^18957691 is an apocalyptic number.

18957691 is a deficient number, since it is larger than the sum of its proper divisors (1).

18957691 is an equidigital number, since it uses as much as digits as its factorization.

18957691 is an evil number, because the sum of its binary digits is even.

The product of its digits is 136080, while the sum is 46.

The square root of 18957691 is about 4354.0430636364. The cubic root of 18957691 is about 266.6419520498.

The spelling of 18957691 in words is "eighteen million, nine hundred fifty-seven thousand, six hundred ninety-one".