21302145 has 12 divisors (see below), whose sum is σ = 36923796. Its totient is φ = 11361120.

The previous prime is 21302143. The next prime is 21302147. The reversal of 21302145 is 54120312.

It is an interprime number because it is at equal distance from previous prime (21302143) and next prime (21302147).

It can be written as a sum of positive squares in 2 ways, for example, as 9585216 + 11716929 = 3096^2 + 3423^2 .

It is not a de Polignac number, because 21302145 - 2¹ = 21302143 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21302143) 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, 236646 + ... + 236735.

It is an arithmetic number, because the mean of its divisors is an integer number (3076983).

Almost surely, 2^21302145 is an apocalyptic number.

It is an amenable number.

21302145 is a deficient number, since it is larger than the sum of its proper divisors (15621651).

21302145 is a wasteful number, since it uses less digits than its factorization.

21302145 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 473392 (or 473389 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 18.

The square root of 21302145 is about 4615.4246825184. The cubic root of 21302145 is about 277.2092889324.

Adding to 21302145 its reverse (54120312), we get a palindrome (75422457).

The spelling of 21302145 in words is "twenty-one million, three hundred two thousand, one hundred forty-five".