1157556661 has 2 divisors, whose sum is σ = 1157556662. Its totient is φ = 1157556660.

The previous prime is 1157556643. The next prime is 1157556671. The reversal of 1157556661 is 1666557511.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 769230225 + 388326436 = 27735^2 + 19706^2 .

It is a cyclic number.

It is not a de Polignac number, because 1157556661 - 2⁵ = 1157556629 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1157556641) 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, 578778330 + 578778331.

It is an arithmetic number, because the mean of its divisors is an integer number (578778331).

Almost surely, 2^1157556661 is an apocalyptic number.

It is an amenable number.

1157556661 is a deficient number, since it is larger than the sum of its proper divisors (1).

1157556661 is an equidigital number, since it uses as much as digits as its factorization.

1157556661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 189000, while the sum is 43.

The square root of 1157556661 is about 34022.8843721399. The cubic root of 1157556661 is about 1049.9793377642.

The spelling of 1157556661 in words is "one billion, one hundred fifty-seven million, five hundred fifty-six thousand, six hundred sixty-one".