1604851991 has 2 divisors, whose sum is σ = 1604851992. Its totient is φ = 1604851990.

The previous prime is 1604851943. The next prime is 1604851993. The reversal of 1604851991 is 1991584061.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1604851991 - 2¹⁴ = 1604835607 is a prime.

Together with 1604851993, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1604851993) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 802425995 + 802425996.

It is an arithmetic number, because the mean of its divisors is an integer number (802425996).

Almost surely, 2^1604851991 is an apocalyptic number.

1604851991 is a deficient number, since it is larger than the sum of its proper divisors (1).

1604851991 is an equidigital number, since it uses as much as digits as its factorization.

1604851991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 77760, while the sum is 44.

The square root of 1604851991 is about 40060.6039769747. The cubic root of 1604851991 is about 1170.7881778589.

The spelling of 1604851991 in words is "one billion, six hundred four million, eight hundred fifty-one thousand, nine hundred ninety-one".