105540021 has 12 divisors (see below), whose sum is σ = 156567372. Its totient is φ = 68458176.

The previous prime is 105539999. The next prime is 105540053. The reversal of 105540021 is 120045501.

105540021 is a `hidden beast` number, since 105 + 540 + 0 + 21 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 41139396 + 64400625 = 6414^2 + 8025^2 .

It is not a de Polignac number, because 105540021 - 2¹¹ = 105537973 is a prime.

It is a super-2 number, since 2×105540021² = 22277392065360882, which contains 22 as substring.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 105539976 and 105540003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (105540121) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 158136 + ... + 158801.

It is an arithmetic number, because the mean of its divisors is an integer number (13047281).

Almost surely, 2^105540021 is an apocalyptic number.

It is an amenable number.

105540021 is a deficient number, since it is larger than the sum of its proper divisors (51027351).

105540021 is a wasteful number, since it uses less digits than its factorization.

105540021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 316980 (or 316977 counting only the distinct ones).

The product of its (nonzero) digits is 200, while the sum is 18.

The square root of 105540021 is about 10273.2672991605. The cubic root of 105540021 is about 472.5767944384.

Adding to 105540021 its reverse (120045501), we get a palindrome (225585522).

The spelling of 105540021 in words is "one hundred five million, five hundred forty thousand, twenty-one".