1659666121 has 3 divisors (see below), whose sum is σ = 1659706861. Its totient is φ = 1659625382.

The previous prime is 1659666103. The next prime is 1659666133. The reversal of 1659666121 is 1216669561.

The square root of 1659666121 is 40739.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is not a de Polignac number, because 1659666121 - 2¹⁷ = 1659535049 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1659666161) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 20370 + ... + 61108.

Almost surely, 2^1659666121 is an apocalyptic number.

1659666121 is the 40739-th square number.

1659666121 is the 20370-th centered octagonal number.

It is an amenable number.

1659666121 is a deficient number, since it is larger than the sum of its proper divisors (40740).

1659666121 is an frugal number, since it uses more digits than its factorization.

1659666121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 81478 (or 40739 counting only the distinct ones).

The product of its digits is 116640, while the sum is 43.

The cubic root of 1659666121 is about 1183.9687589247.

The spelling of 1659666121 in words is "one billion, six hundred fifty-nine million, six hundred sixty-six thousand, one hundred twenty-one".