21248081 has 2 divisors, whose sum is σ = 21248082. Its totient is φ = 21248080.

The previous prime is 21248057. The next prime is 21248093. The reversal of 21248081 is 18084212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11669056 + 9579025 = 3416^2 + 3095^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21248081 is a prime.

It is a super-3 number, since 3×21248081³ (a number of 23 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a self number, because there is not a number n which added to its sum of digits gives 21248081.

It is not a weakly prime, because it can be changed into another prime (21248281) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10624040 + 10624041.

It is an arithmetic number, because the mean of its divisors is an integer number (10624041).

Almost surely, 2^21248081 is an apocalyptic number.

It is an amenable number.

21248081 is a deficient number, since it is larger than the sum of its proper divisors (1).

21248081 is an equidigital number, since it uses as much as digits as its factorization.

21248081 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1024, while the sum is 26.

The square root of 21248081 is about 4609.5640791728. The cubic root of 21248081 is about 276.9745748579.

The spelling of 21248081 in words is "twenty-one million, two hundred forty-eight thousand, eighty-one".