21106145 has 4 divisors (see below), whose sum is σ = 25327380. Its totient is φ = 16884912.

The previous prime is 21106121. The next prime is 21106147. The reversal of 21106145 is 54160112.

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 15147664 + 5958481 = 3892^2 + 2441^2 .

It is a cyclic number.

It is not a de Polignac number, because 21106145 - 2¹⁰ = 21105121 is a prime.

It is a super-2 number, since 2×21106145² = 890938713522050, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21106147) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2110610 + ... + 2110619.

It is an arithmetic number, because the mean of its divisors is an integer number (6331845).

Almost surely, 2^21106145 is an apocalyptic number.

It is an amenable number.

21106145 is a deficient number, since it is larger than the sum of its proper divisors (4221235).

21106145 is an equidigital number, since it uses as much as digits as its factorization.

21106145 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4221234.

The product of its (nonzero) digits is 240, while the sum is 20.

The square root of 21106145 is about 4594.1424662281. The cubic root of 21106145 is about 276.3564715881.

Adding to 21106145 its reverse (54160112), we get a palindrome (75266257).

The spelling of 21106145 in words is "twenty-one million, one hundred six thousand, one hundred forty-five".