1681391559 has 4 divisors (see below), whose sum is σ = 2241855416. Its totient is φ = 1120927704.

The previous prime is 1681391549. The next prime is 1681391561. The reversal of 1681391559 is 9551931861.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 9551931861 = 3 ⋅3183977287.

It is not a de Polignac number, because 1681391559 - 2⁸ = 1681391303 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1681391539) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 280231924 + ... + 280231929.

It is an arithmetic number, because the mean of its divisors is an integer number (560463854).

Almost surely, 2^1681391559 is an apocalyptic number.

1681391559 is a deficient number, since it is larger than the sum of its proper divisors (560463857).

1681391559 is an equidigital number, since it uses as much as digits as its factorization.

1681391559 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 560463856.

The product of its digits is 291600, while the sum is 48.

The square root of 1681391559 is about 41004.7748317193. The cubic root of 1681391559 is about 1189.1125268782.

The spelling of 1681391559 in words is "one billion, six hundred eighty-one million, three hundred ninety-one thousand, five hundred fifty-nine".