1668355537 has 4 divisors (see below), whose sum is σ = 1766494116. Its totient is φ = 1570216960.

The previous prime is 1668355523. The next prime is 1668355541. The reversal of 1668355537 is 7355538661.

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 1310729616 + 357625921 = 36204^2 + 18911^2 .

It is a cyclic number.

It is not a de Polignac number, because 1668355537 - 2¹⁵ = 1668322769 is a prime.

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1668355547) 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, 49069264 + ... + 49069297.

It is an arithmetic number, because the mean of its divisors is an integer number (441623529).

Almost surely, 2^1668355537 is an apocalyptic number.

1668355537 is a gapful number since it is divisible by the number (17) formed by its first and last digit.

It is an amenable number.

1668355537 is a deficient number, since it is larger than the sum of its proper divisors (98138579).

1668355537 is an equidigital number, since it uses as much as digits as its factorization.

1668355537 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 98138578.

The product of its digits is 2268000, while the sum is 49.

The square root of 1668355537 is about 40845.5081618530. The cubic root of 1668355537 is about 1186.0314417413.

The spelling of 1668355537 in words is "one billion, six hundred sixty-eight million, three hundred fifty-five thousand, five hundred thirty-seven".