1913157661 has 2 divisors, whose sum is σ = 1913157662. Its totient is φ = 1913157660.

The previous prime is 1913157643. The next prime is 1913157683. The reversal of 1913157661 is 1667513191.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1278420025 + 634737636 = 35755^2 + 25194^2 .

It is an emirp because it is prime and its reverse (1667513191) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1913157661 - 2²¹ = 1911060509 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1913157691) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 956578830 + 956578831.

It is an arithmetic number, because the mean of its divisors is an integer number (956578831).

Almost surely, 2^1913157661 is an apocalyptic number.

It is an amenable number.

1913157661 is a deficient number, since it is larger than the sum of its proper divisors (1).

1913157661 is an equidigital number, since it uses as much as digits as its factorization.

1913157661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 34020, while the sum is 40.

The square root of 1913157661 is about 43739.6577604352. The cubic root of 1913157661 is about 1241.4148048788.

The spelling of 1913157661 in words is "one billion, nine hundred thirteen million, one hundred fifty-seven thousand, six hundred sixty-one".