161720725436 has 12 divisors (see below), whose sum is σ = 284447876328. Its totient is φ = 80449903632.

The previous prime is 161720725421. The next prime is 161720725459. The reversal of 161720725436 is 634527027161.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 102613886 + ... + 102615461.

It is an arithmetic number, because the mean of its divisors is an integer number (23703989694).

Almost surely, 2^161720725436 is an apocalyptic number.

It is an amenable number.

161720725436 is a deficient number, since it is larger than the sum of its proper divisors (122727150892).

161720725436 is a wasteful number, since it uses less digits than its factorization.

161720725436 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 205229548 (or 205229546 counting only the distinct ones).

The product of its (nonzero) digits is 423360, while the sum is 44.

The spelling of 161720725436 in words is "one hundred sixty-one billion, seven hundred twenty million, seven hundred twenty-five thousand, four hundred thirty-six".