1609817491 has 2 divisors, whose sum is σ = 1609817492. Its totient is φ = 1609817490.

The previous prime is 1609817471. The next prime is 1609817593. The reversal of 1609817491 is 1947189061.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1609817491 - 2⁵ = 1609817459 is a prime.

It is not a weakly prime, because it can be changed into another prime (1609817401) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 804908745 + 804908746.

It is an arithmetic number, because the mean of its divisors is an integer number (804908746).

Almost surely, 2^1609817491 is an apocalyptic number.

1609817491 is a deficient number, since it is larger than the sum of its proper divisors (1).

1609817491 is an equidigital number, since it uses as much as digits as its factorization.

1609817491 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 108864, while the sum is 46.

The square root of 1609817491 is about 40122.5309645341. The cubic root of 1609817491 is about 1171.9944289030.

The spelling of 1609817491 in words is "one billion, six hundred nine million, eight hundred seventeen thousand, four hundred ninety-one".