1667338921 has 4 divisors (see below), whose sum is σ = 1669285332. Its totient is φ = 1665392512.

The previous prime is 1667338891. The next prime is 1667338961. The reversal of 1667338921 is 1298337661.

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 1431562896 + 235776025 = 37836^2 + 15355^2 .

It is a cyclic number.

It is not a de Polignac number, because 1667338921 - 2²³ = 1658950313 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1667338961) 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, 971920 + ... + 973633.

It is an arithmetic number, because the mean of its divisors is an integer number (417321333).

Almost surely, 2^1667338921 is an apocalyptic number.

It is an amenable number.

1667338921 is a deficient number, since it is larger than the sum of its proper divisors (1946411).

1667338921 is an equidigital number, since it uses as much as digits as its factorization.

1667338921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1946410.

The product of its digits is 326592, while the sum is 46.

The square root of 1667338921 is about 40833.0616167830. The cubic root of 1667338921 is about 1185.7904891979.

The spelling of 1667338921 in words is "one billion, six hundred sixty-seven million, three hundred thirty-eight thousand, nine hundred twenty-one".