1138657561 has 2 divisors, whose sum is σ = 1138657562. Its totient is φ = 1138657560.

The previous prime is 1138657493. The next prime is 1138657609. The reversal of 1138657561 is 1657568311.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1138657536 + 25 = 33744^2 + 5^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1138657561 is a prime.

It is not a weakly prime, because it can be changed into another prime (1138657361) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 569328780 + 569328781.

It is an arithmetic number, because the mean of its divisors is an integer number (569328781).

Almost surely, 2^1138657561 is an apocalyptic number.

It is an amenable number.

1138657561 is a deficient number, since it is larger than the sum of its proper divisors (1).

1138657561 is an equidigital number, since it uses as much as digits as its factorization.

1138657561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 151200, while the sum is 43.

The square root of 1138657561 is about 33744.0003704362. Note that the first 3 decimals coincide. The cubic root of 1138657561 is about 1044.2337158352.

The spelling of 1138657561 in words is "one billion, one hundred thirty-eight million, six hundred fifty-seven thousand, five hundred sixty-one".