21008293 has 2 divisors, whose sum is σ = 21008294. Its totient is φ = 21008292.

The previous prime is 21008291. The next prime is 21008329. The reversal of 21008293 is 39280012.

Together with next prime (21008329) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10876804 + 10131489 = 3298^2 + 3183^2 .

It is a cyclic number.

It is not a de Polignac number, because 21008293 - 2¹ = 21008291 is a prime.

It is a super-5 number, since 5×21008293⁵ (a number of 38 digits) contains 55555 as substring.

Together with 21008291, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21008291) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10504146 + 10504147.

It is an arithmetic number, because the mean of its divisors is an integer number (10504147).

Almost surely, 2^21008293 is an apocalyptic number.

It is an amenable number.

21008293 is a deficient number, since it is larger than the sum of its proper divisors (1).

21008293 is an equidigital number, since it uses as much as digits as its factorization.

21008293 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 864, while the sum is 25.

The square root of 21008293 is about 4583.4804461239. The cubic root of 21008293 is about 275.9287299351.

The spelling of 21008293 in words is "twenty-one million, eight thousand, two hundred ninety-three".