105720821 has 2 divisors, whose sum is σ = 105720822. Its totient is φ = 105720820.

The previous prime is 105720809. The next prime is 105720829. The reversal of 105720821 is 128027501.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 53085796 + 52635025 = 7286^2 + 7255^2 .

It is a cyclic number.

It is not a de Polignac number, because 105720821 - 2¹⁰ = 105719797 is a prime.

It is a super-2 number, since 2×105720821² = 22353783985828082, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (105720829) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 52860410 + 52860411.

It is an arithmetic number, because the mean of its divisors is an integer number (52860411).

Almost surely, 2^105720821 is an apocalyptic number.

It is an amenable number.

105720821 is a deficient number, since it is larger than the sum of its proper divisors (1).

105720821 is an equidigital number, since it uses as much as digits as its factorization.

105720821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1120, while the sum is 26.

The square root of 105720821 is about 10282.0630711934. The cubic root of 105720821 is about 472.8464966803.

The spelling of 105720821 in words is "one hundred five million, seven hundred twenty thousand, eight hundred twenty-one".