1668811657 has 4 divisors (see below), whose sum is σ = 1704318336. Its totient is φ = 1633304980.

The previous prime is 1668811649. The next prime is 1668811673. The reversal of 1668811657 is 7561188661.

It is a happy number.

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 1668811657 - 2³ = 1668811649 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1668811657.

It is not an unprimeable number, because it can be changed into a prime (1668811687) 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, 17753269 + ... + 17753362.

It is an arithmetic number, because the mean of its divisors is an integer number (426079584).

Almost surely, 2^1668811657 is an apocalyptic number.

It is an amenable number.

1668811657 is a deficient number, since it is larger than the sum of its proper divisors (35506679).

1668811657 is an equidigital number, since it uses as much as digits as its factorization.

1668811657 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35506678.

The product of its digits is 483840, while the sum is 49.

The square root of 1668811657 is about 40851.0912583740. The cubic root of 1668811657 is about 1186.1395169001.

The spelling of 1668811657 in words is "one billion, six hundred sixty-eight million, eight hundred eleven thousand, six hundred fifty-seven".