21248641 has 2 divisors, whose sum is σ = 21248642. Its totient is φ = 21248640.

The previous prime is 21248639. The next prime is 21248651. The reversal of 21248641 is 14684212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12960000 + 8288641 = 3600^2 + 2879^2 .

It is a cyclic number.

It is not a de Polignac number, because 21248641 - 2¹ = 21248639 is a prime.

Together with 21248639, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21248651) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10624320 + 10624321.

It is an arithmetic number, because the mean of its divisors is an integer number (10624321).

Almost surely, 2^21248641 is an apocalyptic number.

It is an amenable number.

21248641 is a deficient number, since it is larger than the sum of its proper divisors (1).

21248641 is an equidigital number, since it uses as much as digits as its factorization.

21248641 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3072, while the sum is 28.

The square root of 21248641 is about 4609.6248220435. The cubic root of 21248641 is about 276.9770080879.

The spelling of 21248641 in words is "twenty-one million, two hundred forty-eight thousand, six hundred forty-one".