18979591 has 2 divisors, whose sum is σ = 18979592. Its totient is φ = 18979590.

The previous prime is 18979589. The next prime is 18979603. The reversal of 18979591 is 19597981.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 18979591 - 2¹ = 18979589 is a prime.

Together with 18979589, 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 (18979511) 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, 9489795 + 9489796.

It is an arithmetic number, because the mean of its divisors is an integer number (9489796).

Almost surely, 2^18979591 is an apocalyptic number.

18979591 is a deficient number, since it is larger than the sum of its proper divisors (1).

18979591 is an equidigital number, since it uses as much as digits as its factorization.

18979591 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 204120, while the sum is 49.

The square root of 18979591 is about 4356.5572416760. The cubic root of 18979591 is about 266.7445878192.

The spelling of 18979591 in words is "eighteen million, nine hundred seventy-nine thousand, five hundred ninety-one".