105666821 has 4 divisors (see below), whose sum is σ = 113795052. Its totient is φ = 97538592.

The previous prime is 105666791. The next prime is 105666863. The reversal of 105666821 is 128666501.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 73017025 + 32649796 = 8545^2 + 5714^2 .

It is a cyclic number.

It is not a de Polignac number, because 105666821 - 2¹⁰ = 105665797 is a prime.

It is a super-2 number, since 2×105666821² = 22330954120492082, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (105666871) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4064096 + ... + 4064121.

It is an arithmetic number, because the mean of its divisors is an integer number (28448763).

Almost surely, 2^105666821 is an apocalyptic number.

It is an amenable number.

105666821 is a deficient number, since it is larger than the sum of its proper divisors (8128231).

105666821 is an equidigital number, since it uses as much as digits as its factorization.

105666821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8128230.

The product of its (nonzero) digits is 17280, while the sum is 35.

The square root of 105666821 is about 10279.4368036386. The cubic root of 105666821 is about 472.7659762455.

The spelling of 105666821 in words is "one hundred five million, six hundred sixty-six thousand, eight hundred twenty-one".