21302081 has 2 divisors, whose sum is σ = 21302082. Its totient is φ = 21302080.

The previous prime is 21302063. The next prime is 21302093. The reversal of 21302081 is 18020312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13690000 + 7612081 = 3700^2 + 2759^2 .

It is a cyclic number.

It is not a de Polignac number, because 21302081 - 2¹⁰ = 21301057 is a prime.

It is a super-2 number, since 2×21302081² = 907557309861122, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21302051) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10651040 + 10651041.

It is an arithmetic number, because the mean of its divisors is an integer number (10651041).

Almost surely, 2^21302081 is an apocalyptic number.

It is an amenable number.

21302081 is a deficient number, since it is larger than the sum of its proper divisors (1).

21302081 is an equidigital number, since it uses as much as digits as its factorization.

21302081 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 96, while the sum is 17.

The square root of 21302081 is about 4615.4177492400. The cubic root of 21302081 is about 277.2090113170.

Adding to 21302081 its reverse (18020312), we get a palindrome (39322393).

The spelling of 21302081 in words is "twenty-one million, three hundred two thousand, eighty-one".