161720725707 has 24 divisors (see below), whose sum is σ = 236552110080. Its totient is φ = 106457788080.

The previous prime is 161720725643. The next prime is 161720725709. The reversal of 161720725707 is 707527027161.

161720725707 is a `hidden beast` number, since 1 + 6 + 1 + 7 + 2 + 0 + 72 + 570 + 7 = 666.

It is not a de Polignac number, because 161720725707 - 2⁶ = 161720725643 is a prime.

It is not an unprimeable number, because it can be changed into a prime (161720725709) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 94107 + ... + 576452.

It is an arithmetic number, because the mean of its divisors is an integer number (9856337920).

Almost surely, 2^161720725707 is an apocalyptic number.

161720725707 is a deficient number, since it is larger than the sum of its proper divisors (74831384373).

161720725707 is a wasteful number, since it uses less digits than its factorization.

161720725707 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 670903 (or 670900 counting only the distinct ones).

The product of its (nonzero) digits is 288120, while the sum is 45.

The spelling of 161720725707 in words is "one hundred sixty-one billion, seven hundred twenty million, seven hundred twenty-five thousand, seven hundred seven".