660281621 has 2 divisors, whose sum is σ = 660281622. Its totient is φ = 660281620.

The previous prime is 660281593. The next prime is 660281623. The reversal of 660281621 is 126182066.

660281621 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 653364721 + 6916900 = 25561^2 + 2630^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-660281621 is a prime.

Together with 660281623, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (660281623) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330140810 + 330140811.

It is an arithmetic number, because the mean of its divisors is an integer number (330140811).

Almost surely, 2^660281621 is an apocalyptic number.

It is an amenable number.

660281621 is a deficient number, since it is larger than the sum of its proper divisors (1).

660281621 is an equidigital number, since it uses as much as digits as its factorization.

660281621 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6912, while the sum is 32.

The square root of 660281621 is about 25695.9456140458. The cubic root of 660281621 is about 870.7825877672.

The spelling of 660281621 in words is "six hundred sixty million, two hundred eighty-one thousand, six hundred twenty-one".