161557818853 has 4 divisors (see below), whose sum is σ = 171061219980. Its totient is φ = 152054417728.

The previous prime is 161557818841. The next prime is 161557818857. The reversal of 161557818853 is 358818755161.

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 103927574884 + 57630243969 = 322378^2 + 240063^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-161557818853 is a prime.

It is a super-2 number, since 2×161557818853² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161557818857) 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, 4751700538 + ... + 4751700571.

It is an arithmetic number, because the mean of its divisors is an integer number (42765304995).

Almost surely, 2^161557818853 is an apocalyptic number.

It is an amenable number.

161557818853 is a deficient number, since it is larger than the sum of its proper divisors (9503401127).

161557818853 is an equidigital number, since it uses as much as digits as its factorization.

161557818853 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9503401126.

The product of its digits is 8064000, while the sum is 58.

The spelling of 161557818853 in words is "one hundred sixty-one billion, five hundred fifty-seven million, eight hundred eighteen thousand, eight hundred fifty-three".