105818921 has 4 divisors (see below), whose sum is σ = 113958852. Its totient is φ = 97678992.

The previous prime is 105818887. The next prime is 105818939. The reversal of 105818921 is 129818501.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 129818501 = 863 ⋅150427.

It can be written as a sum of positive squares in 2 ways, for example, as 20976400 + 84842521 = 4580^2 + 9211^2 .

It is a cyclic number.

It is not a de Polignac number, because 105818921 - 2⁶ = 105818857 is a prime.

It is a super-2 number, since 2×105818921² = 22395288083208482, which contains 22 as substring.

It is an alternating number because its digits alternate between odd and even.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (105818021) 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, 4069946 + ... + 4069971.

It is an arithmetic number, because the mean of its divisors is an integer number (28489713).

Almost surely, 2^105818921 is an apocalyptic number.

It is an amenable number.

105818921 is a deficient number, since it is larger than the sum of its proper divisors (8139931).

105818921 is an equidigital number, since it uses as much as digits as its factorization.

105818921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8139930.

The product of its (nonzero) digits is 5760, while the sum is 35.

The square root of 105818921 is about 10286.8324084725. The cubic root of 105818921 is about 472.9927053481.

The spelling of 105818921 in words is "one hundred five million, eight hundred eighteen thousand, nine hundred twenty-one".