1685868661 has 4 divisors (see below), whose sum is σ = 1692279072. Its totient is φ = 1679458252.

The previous prime is 1685868637. The next prime is 1685868677. The reversal of 1685868661 is 1668685861.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1685868661 - 2¹¹ = 1685866613 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 (1685868061) 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, 3204811 + ... + 3205336.

It is an arithmetic number, because the mean of its divisors is an integer number (423069768).

Almost surely, 2^1685868661 is an apocalyptic number.

It is an amenable number.

1685868661 is a deficient number, since it is larger than the sum of its proper divisors (6410411).

1685868661 is an equidigital number, since it uses as much as digits as its factorization.

1685868661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6410410.

The product of its digits is 3317760, while the sum is 55.

The square root of 1685868661 is about 41059.3309857820. The cubic root of 1685868661 is about 1190.1670224336.

The spelling of 1685868661 in words is "one billion, six hundred eighty-five million, eight hundred sixty-eight thousand, six hundred sixty-one".