21303145 has 4 divisors (see below), whose sum is σ = 25563780. Its totient is φ = 17042512.

The previous prime is 21303143. The next prime is 21303187. The reversal of 21303145 is 54130312.

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 13220496 + 8082649 = 3636^2 + 2843^2 .

It is a cyclic number.

It is not a de Polignac number, because 21303145 - 2¹ = 21303143 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21303143) 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, 2130310 + ... + 2130319.

It is an arithmetic number, because the mean of its divisors is an integer number (6390945).

Almost surely, 2^21303145 is an apocalyptic number.

It is an amenable number.

21303145 is a deficient number, since it is larger than the sum of its proper divisors (4260635).

21303145 is an equidigital number, since it uses as much as digits as its factorization.

21303145 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4260634.

The product of its (nonzero) digits is 360, while the sum is 19.

The square root of 21303145 is about 4615.5330136399. The cubic root of 21303145 is about 277.2136266013.

Adding to 21303145 its reverse (54130312), we get a palindrome (75433457).

The spelling of 21303145 in words is "twenty-one million, three hundred three thousand, one hundred forty-five".