21142145 has 4 divisors (see below), whose sum is σ = 25370580. Its totient is φ = 16913712.

The previous prime is 21142141. The next prime is 21142153. The reversal of 21142145 is 54124112.

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 4682896 + 16459249 = 2164^2 + 4057^2 .

It is a cyclic number.

It is not a de Polignac number, because 21142145 - 2² = 21142141 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21142141) 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, 2114210 + ... + 2114219.

It is an arithmetic number, because the mean of its divisors is an integer number (6342645).

Almost surely, 2^21142145 is an apocalyptic number.

It is an amenable number.

21142145 is a deficient number, since it is larger than the sum of its proper divisors (4228435).

21142145 is an equidigital number, since it uses as much as digits as its factorization.

21142145 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4228434.

The product of its digits is 320, while the sum is 20.

The square root of 21142145 is about 4598.0588295497. The cubic root of 21142145 is about 276.5135061370.

Adding to 21142145 its reverse (54124112), we get a palindrome (75266257).

The spelling of 21142145 in words is "twenty-one million, one hundred forty-two thousand, one hundred forty-five".