21302161 has 2 divisors, whose sum is σ = 21302162. Its totient is φ = 21302160.

The previous prime is 21302147. The next prime is 21302189. The reversal of 21302161 is 16120312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20611600 + 690561 = 4540^2 + 831^2 .

It is a cyclic number.

It is not a de Polignac number, because 21302161 - 2⁵ = 21302129 is a prime.

It is not a weakly prime, because it can be changed into another prime (21302111) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10651080 + 10651081.

It is an arithmetic number, because the mean of its divisors is an integer number (10651081).

Almost surely, 2^21302161 is an apocalyptic number.

It is an amenable number.

21302161 is a deficient number, since it is larger than the sum of its proper divisors (1).

21302161 is an equidigital number, since it uses as much as digits as its factorization.

21302161 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 72, while the sum is 16.

The square root of 21302161 is about 4615.4264158364. The cubic root of 21302161 is about 277.2093583362.

Adding to 21302161 its reverse (16120312), we get a palindrome (37422473).

The spelling of 21302161 in words is "twenty-one million, three hundred two thousand, one hundred sixty-one".