161973246681 has 9 divisors (see below), whose sum is σ = 233963100319. Its totient is φ = 107981359536.

The previous prime is 161973246613. The next prime is 161973246749. The reversal of 161973246681 is 186642379161.

The square root of 161973246681 is 402459.

It is a perfect power (a square), and thus also a powerful number.

161973246681 is a `hidden beast` number, since 1 + 61 + 97 + 32 + 466 + 8 + 1 = 666.

It is an interprime number because it is at equal distance from previous prime (161973246613) and next prime (161973246749).

It can be written as a sum of positive squares in only one way, i.e., 59070872025 + 102902374656 = 243045^2 + 320784^2 .

It is a tau number, because it is divible by the number of its divisors (9).

It is not a de Polignac number, because 161973246681 - 2⁷ = 161973246553 is a prime.

It is a super-2 number, since 2×161973246681² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161973246181) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 1140301 + ... + 1274453.

Almost surely, 2^161973246681 is an apocalyptic number.

161973246681 is the 402459-th square number.

161973246681 is the 201230-th centered octagonal number.

It is an amenable number.

161973246681 is a deficient number, since it is larger than the sum of its proper divisors (71989853638).

161973246681 is an frugal number, since it uses more digits than its factorization.

161973246681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 268312 (or 134156 counting only the distinct ones).

The product of its digits is 2612736, while the sum is 54.

The spelling of 161973246681 in words is "one hundred sixty-one billion, nine hundred seventy-three million, two hundred forty-six thousand, six hundred eighty-one".