21863081 has 2 divisors, whose sum is σ = 21863082. Its totient is φ = 21863080.

The previous prime is 21863069. The next prime is 21863119. The reversal of 21863081 is 18036812.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15335056 + 6528025 = 3916^2 + 2555^2 .

It is a cyclic number.

It is not a de Polignac number, because 21863081 - 2¹⁸ = 21600937 is a prime.

It is a super-2 number, since 2×21863081² = 955988621625122, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21863011) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10931540 + 10931541.

It is an arithmetic number, because the mean of its divisors is an integer number (10931541).

Almost surely, 2^21863081 is an apocalyptic number.

It is an amenable number.

21863081 is a deficient number, since it is larger than the sum of its proper divisors (1).

21863081 is an equidigital number, since it uses as much as digits as its factorization.

21863081 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2304, while the sum is 29.

The square root of 21863081 is about 4675.7973651560. The cubic root of 21863081 is about 279.6214314216.

Adding to 21863081 its reverse (18036812), we get a palindrome (39899893).

The spelling of 21863081 in words is "twenty-one million, eight hundred sixty-three thousand, eighty-one".