105161981 has 4 divisors (see below), whose sum is σ = 106092732. Its totient is φ = 104231232.

The previous prime is 105161977. The next prime is 105162019. The reversal of 105161981 is 189161501.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 189161501 = 37 ⋅5112473.

It can be written as a sum of positive squares in 2 ways, for example, as 39000025 + 66161956 = 6245^2 + 8134^2 .

It is a cyclic number.

It is not a de Polignac number, because 105161981 - 2² = 105161977 is a prime.

It is a super-2 number, since 2×105161981² = 22118084495688722, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (105161921) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 465206 + ... + 465431.

It is an arithmetic number, because the mean of its divisors is an integer number (26523183).

Almost surely, 2^105161981 is an apocalyptic number.

It is an amenable number.

105161981 is a deficient number, since it is larger than the sum of its proper divisors (930751).

105161981 is an equidigital number, since it uses as much as digits as its factorization.

105161981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 930750.

The product of its (nonzero) digits is 2160, while the sum is 32.

The square root of 105161981 is about 10254.8515835189. The cubic root of 105161981 is about 472.0118691954.

The spelling of 105161981 in words is "one hundred five million, one hundred sixty-one thousand, nine hundred eighty-one".