161236265557 has 4 divisors (see below), whose sum is σ = 162127073836. Its totient is φ = 160345457280.

The previous prime is 161236265521. The next prime is 161236265581. The reversal of 161236265557 is 755562632161.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 14842792561 + 146393472996 = 121831^2 + 382614^2 .

It is a cyclic number.

It is not a de Polignac number, because 161236265557 - 2⁷ = 161236265429 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 161236265557.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161236260557) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 445403868 + ... + 445404229.

It is an arithmetic number, because the mean of its divisors is an integer number (40531768459).

Almost surely, 2^161236265557 is an apocalyptic number.

It is an amenable number.

161236265557 is a deficient number, since it is larger than the sum of its proper divisors (890808279).

161236265557 is an equidigital number, since it uses as much as digits as its factorization.

161236265557 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 890808278.

The product of its digits is 2268000, while the sum is 49.

The spelling of 161236265557 in words is "one hundred sixty-one billion, two hundred thirty-six million, two hundred sixty-five thousand, five hundred fifty-seven".