161644559477 has 2 divisors, whose sum is σ = 161644559478. Its totient is φ = 161644559476.

The previous prime is 161644559473. The next prime is 161644559519. The reversal of 161644559477 is 774955446161.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 110517018481 + 51127540996 = 332441^2 + 226114^2 .

It is a cyclic number.

It is not a de Polignac number, because 161644559477 - 2² = 161644559473 is a prime.

It is a super-2 number, since 2×161644559477² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (161644559473) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80822279738 + 80822279739.

It is an arithmetic number, because the mean of its divisors is an integer number (80822279739).

Almost surely, 2^161644559477 is an apocalyptic number.

It is an amenable number.

161644559477 is a deficient number, since it is larger than the sum of its proper divisors (1).

161644559477 is an equidigital number, since it uses as much as digits as its factorization.

161644559477 is an evil number, because the sum of its binary digits is even.

The product of its digits is 25401600, while the sum is 59.

The spelling of 161644559477 in words is "one hundred sixty-one billion, six hundred forty-four million, five hundred fifty-nine thousand, four hundred seventy-seven".