1667638061 has 4 divisors (see below), whose sum is σ = 1690482492. Its totient is φ = 1644793632.

The previous prime is 1667638043. The next prime is 1667638073. The reversal of 1667638061 is 1608367661.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1608367661 = 487 ⋅3302603.

It can be written as a sum of positive squares in 2 ways, for example, as 1262380900 + 405257161 = 35530^2 + 20131^2 .

It is a cyclic number.

It is not a de Polignac number, because 1667638061 - 2¹⁸ = 1667375917 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 (1667638361) 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, 11422106 + ... + 11422251.

It is an arithmetic number, because the mean of its divisors is an integer number (422620623).

Almost surely, 2^1667638061 is an apocalyptic number.

It is an amenable number.

1667638061 is a deficient number, since it is larger than the sum of its proper divisors (22844431).

1667638061 is an equidigital number, since it uses as much as digits as its factorization.

1667638061 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22844430.

The product of its (nonzero) digits is 217728, while the sum is 44.

The square root of 1667638061 is about 40836.7244156531. The cubic root of 1667638061 is about 1185.8613998271.

The spelling of 1667638061 in words is "one billion, six hundred sixty-seven million, six hundred thirty-eight thousand, sixty-one".