1608138991 has 2 divisors, whose sum is σ = 1608138992. Its totient is φ = 1608138990.

The previous prime is 1608138949. The next prime is 1608139019. The reversal of 1608138991 is 1998318061.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1608138991 - 2¹⁹ = 1607614703 is a prime.

It is a super-2 number, since 2×1608138991² = 5172222028748996162, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1608138901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 804069495 + 804069496.

It is an arithmetic number, because the mean of its divisors is an integer number (804069496).

Almost surely, 2^1608138991 is an apocalyptic number.

1608138991 is a deficient number, since it is larger than the sum of its proper divisors (1).

1608138991 is an equidigital number, since it uses as much as digits as its factorization.

1608138991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 93312, while the sum is 46.

The square root of 1608138991 is about 40101.6083343299. The cubic root of 1608138991 is about 1171.5869548128.

The spelling of 1608138991 in words is "one billion, six hundred eight million, one hundred thirty-eight thousand, nine hundred ninety-one".