1685359381 has 4 divisors (see below), whose sum is σ = 1686329164. Its totient is φ = 1684389600.

The previous prime is 1685359373. The next prime is 1685359387. The reversal of 1685359381 is 1839535861.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1839535861 = 19319 ⋅95219.

It can be written as a sum of positive squares in 2 ways, for example, as 115218756 + 1570140625 = 10734^2 + 39625^2 .

It is a cyclic number.

It is not a de Polignac number, because 1685359381 - 2³ = 1685359373 is a prime.

It is a super-2 number, since 2×1685359381² = 5680872486249406322, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1685359387) 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, 482280 + ... + 485761.

It is an arithmetic number, because the mean of its divisors is an integer number (421582291).

Almost surely, 2^1685359381 is an apocalyptic number.

It is an amenable number.

1685359381 is a deficient number, since it is larger than the sum of its proper divisors (969783).

1685359381 is an equidigital number, since it uses as much as digits as its factorization.

1685359381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 969782.

The product of its digits is 777600, while the sum is 49.

The square root of 1685359381 is about 41053.1287601810. The cubic root of 1685359381 is about 1190.0471654681.

The spelling of 1685359381 in words is "one billion, six hundred eighty-five million, three hundred fifty-nine thousand, three hundred eighty-one".