1815681685 has 16 divisors (see below), whose sum is σ = 2350517616. Its totient is φ = 1341303808.

The previous prime is 1815681671. The next prime is 1815681691. The reversal of 1815681685 is 5861865181.

It can be written as a sum of positive squares in 8 ways, for example, as 340660849 + 1475020836 = 18457^2 + 38406^2 .

It is not a de Polignac number, because 1815681685 - 2⁷ = 1815681557 is a prime.

It is a super-3 number, since 3×1815681685³ (a number of 29 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 197014 + ... + 206023.

It is an arithmetic number, because the mean of its divisors is an integer number (146907351).

Almost surely, 2^1815681685 is an apocalyptic number.

It is an amenable number.

1815681685 is a deficient number, since it is larger than the sum of its proper divisors (534835931).

1815681685 is a wasteful number, since it uses less digits than its factorization.

1815681685 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 403112.

The product of its digits is 460800, while the sum is 49.

The square root of 1815681685 is about 42610.8165258541. The cubic root of 1815681685 is about 1219.9627519310.

The spelling of 1815681685 in words is "one billion, eight hundred fifteen million, six hundred eighty-one thousand, six hundred eighty-five".