1538611661 has 2 divisors, whose sum is σ = 1538611662. Its totient is φ = 1538611660.

The previous prime is 1538611649. The next prime is 1538611667. The reversal of 1538611661 is 1661168351.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1506914761 + 31696900 = 38819^2 + 5630^2 .

It is a cyclic number.

It is not a de Polignac number, because 1538611661 - 2⁶ = 1538611597 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1538611667) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 769305830 + 769305831.

It is an arithmetic number, because the mean of its divisors is an integer number (769305831).

Almost surely, 2^1538611661 is an apocalyptic number.

It is an amenable number.

1538611661 is a deficient number, since it is larger than the sum of its proper divisors (1).

1538611661 is an equidigital number, since it uses as much as digits as its factorization.

1538611661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 25920, while the sum is 38.

The square root of 1538611661 is about 39225.1406753373. The cubic root of 1538611661 is about 1154.4532212022.

The spelling of 1538611661 in words is "one billion, five hundred thirty-eight million, six hundred eleven thousand, six hundred sixty-one".