21168145 has 8 divisors (see below), whose sum is σ = 26896104. Its totient is φ = 15938304.

The previous prime is 21168143. The next prime is 21168151. The reversal of 21168145 is 54186112.

It can be written as a sum of positive squares in 4 ways, for example, as 11950849 + 9217296 = 3457^2 + 3036^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21168145 - 2¹ = 21168143 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21168143) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 124434 + ... + 124603.

It is an arithmetic number, because the mean of its divisors is an integer number (3362013).

Almost surely, 2^21168145 is an apocalyptic number.

It is an amenable number.

21168145 is a deficient number, since it is larger than the sum of its proper divisors (5727959).

21168145 is a wasteful number, since it uses less digits than its factorization.

21168145 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 249059.

The product of its digits is 1920, while the sum is 28.

The square root of 21168145 is about 4600.8852409074. The cubic root of 21168145 is about 276.6268091484.

The spelling of 21168145 in words is "twenty-one million, one hundred sixty-eight thousand, one hundred forty-five".