1668387221 has 4 divisors (see below), whose sum is σ = 1677708000. Its totient is φ = 1659066444.

The previous prime is 1668387151. The next prime is 1668387251. The reversal of 1668387221 is 1227838661.

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 1668387221 - 2¹⁸ = 1668125077 is a prime.

It is a super-2 number, since 2×1668387221² = 5567031838392205682, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1668387251) 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, 4660121 + ... + 4660478.

It is an arithmetic number, because the mean of its divisors is an integer number (419427000).

Almost surely, 2^1668387221 is an apocalyptic number.

It is an amenable number.

1668387221 is a deficient number, since it is larger than the sum of its proper divisors (9320779).

1668387221 is an equidigital number, since it uses as much as digits as its factorization.

1668387221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9320778.

The product of its digits is 193536, while the sum is 44.

The square root of 1668387221 is about 40845.8960117170. The cubic root of 1668387221 is about 1186.0389497297.

The spelling of 1668387221 in words is "one billion, six hundred sixty-eight million, three hundred eighty-seven thousand, two hundred twenty-one".