161081019801 has 81 divisors (see below), whose sum is σ = 259275122301. Its totient is φ = 96323760000.

The previous prime is 161081019739. The next prime is 161081019833. The reversal of 161081019801 is 108910180161.

The square root of 161081019801 is 401349.

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

It can be written as a sum of positive squares in 4 ways, for example, as 107292278025 + 53788741776 = 327555^2 + 231924^2 .

It is not a de Polignac number, because 161081019801 - 2²⁹ = 160544148889 is a prime.

It is not an unprimeable number, because it can be changed into a prime (161081019101) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 80 ways as a sum of consecutive naturals, for example, 641756926 + ... + 641757176.

Almost surely, 2^161081019801 is an apocalyptic number.

161081019801 is the 401349-th square number.

161081019801 is the 200675-th centered octagonal number.

It is an amenable number.

161081019801 is a deficient number, since it is larger than the sum of its proper divisors (98194102500).

161081019801 is an equidigital number, since it uses as much as digits as its factorization.

161081019801 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 616 (or 308 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 36.

Multiplying 161081019801 by its sum of digits (36), we get a square (5798916712836 = 2408094²).

Adding to 161081019801 its reverse (108910180161), we get a palindrome (269991199962).

The spelling of 161081019801 in words is "one hundred sixty-one billion, eighty-one million, nineteen thousand, eight hundred one".