1659621121 has 2 divisors, whose sum is σ = 1659621122. Its totient is φ = 1659621120.

The previous prime is 1659621079. The next prime is 1659621137. The reversal of 1659621121 is 1211269561.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1257057025 + 402564096 = 35455^2 + 20064^2 .

It is a cyclic number.

It is not a de Polignac number, because 1659621121 - 2¹⁵ = 1659588353 is a prime.

It is not a weakly prime, because it can be changed into another prime (1659621721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 829810560 + 829810561.

It is an arithmetic number, because the mean of its divisors is an integer number (829810561).

Almost surely, 2^1659621121 is an apocalyptic number.

It is an amenable number.

1659621121 is a deficient number, since it is larger than the sum of its proper divisors (1).

1659621121 is an equidigital number, since it uses as much as digits as its factorization.

1659621121 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6480, while the sum is 34.

The square root of 1659621121 is about 40738.4476999308. The cubic root of 1659621121 is about 1183.9580581628.

The spelling of 1659621121 in words is "one billion, six hundred fifty-nine million, six hundred twenty-one thousand, one hundred twenty-one".