105815821 has 2 divisors, whose sum is σ = 105815822. Its totient is φ = 105815820.

The previous prime is 105815789. The next prime is 105815833. The reversal of 105815821 is 128518501.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 105781225 + 34596 = 10285^2 + 186^2 .

It is a cyclic number.

It is not a de Polignac number, because 105815821 - 2⁵ = 105815789 is a prime.

It is a super-2 number, since 2×105815821² = 22393975947808082, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (105815881) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 52907910 + 52907911.

It is an arithmetic number, because the mean of its divisors is an integer number (52907911).

Almost surely, 2^105815821 is an apocalyptic number.

It is an amenable number.

105815821 is a deficient number, since it is larger than the sum of its proper divisors (1).

105815821 is an equidigital number, since it uses as much as digits as its factorization.

105815821 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3200, while the sum is 31.

The square root of 105815821 is about 10286.6817293042. The cubic root of 105815821 is about 472.9880864775.

The spelling of 105815821 in words is "one hundred five million, eight hundred fifteen thousand, eight hundred twenty-one".