1671999685 has 4 divisors (see below), whose sum is σ = 2006399628. Its totient is φ = 1337599744.

The previous prime is 1671999631. The next prime is 1671999689. The reversal of 1671999685 is 5869991761.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 426050881 + 1245948804 = 20641^2 + 35298^2 .

It is a cyclic number.

It is not a de Polignac number, because 1671999685 - 2¹⁵ = 1671966917 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 (1671999689) 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, 167199964 + ... + 167199973.

It is an arithmetic number, because the mean of its divisors is an integer number (501599907).

Almost surely, 2^1671999685 is an apocalyptic number.

It is an amenable number.

1671999685 is a deficient number, since it is larger than the sum of its proper divisors (334399943).

1671999685 is an equidigital number, since it uses as much as digits as its factorization.

1671999685 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 334399942.

The product of its digits is 7348320, while the sum is 61.

The square root of 1671999685 is about 40890.0927487332. The cubic root of 1671999685 is about 1186.8943535441.

The spelling of 1671999685 in words is "one billion, six hundred seventy-one million, nine hundred ninety-nine thousand, six hundred eighty-five".