105212021 has 2 divisors, whose sum is σ = 105212022. Its totient is φ = 105212020.

The previous prime is 105211999. The next prime is 105212039. The reversal of 105212021 is 120212501.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 84180625 + 21031396 = 9175^2 + 4586^2 .

It is an emirp because it is prime and its reverse (120212501) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 105212021 - 2²² = 101017717 is a prime.

It is a super-2 number, since 2×105212021² = 22139138725808882, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 105211987 and 105212005.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (105212071) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 52606010 + 52606011.

It is an arithmetic number, because the mean of its divisors is an integer number (52606011).

Almost surely, 2^105212021 is an apocalyptic number.

It is an amenable number.

105212021 is a deficient number, since it is larger than the sum of its proper divisors (1).

105212021 is an equidigital number, since it uses as much as digits as its factorization.

105212021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 40, while the sum is 14.

The square root of 105212021 is about 10257.2911141295. The cubic root of 105212021 is about 472.0867242852.

Adding to 105212021 its reverse (120212501), we get a palindrome (225424522).

The spelling of 105212021 in words is "one hundred five million, two hundred twelve thousand, twenty-one".