661452250021 has 2 divisors, whose sum is σ = 661452250022. Its totient is φ = 661452250020.

The previous prime is 661452250013. The next prime is 661452250037. The reversal of 661452250021 is 120052254166.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 607286669796 + 54165580225 = 779286^2 + 232735^2 .

It is a cyclic number.

It is not a de Polignac number, because 661452250021 - 2³ = 661452250013 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (661452250001) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330726125010 + 330726125011.

It is an arithmetic number, because the mean of its divisors is an integer number (330726125011).

Almost surely, 2^661452250021 is an apocalyptic number.

It is an amenable number.

661452250021 is a deficient number, since it is larger than the sum of its proper divisors (1).

661452250021 is an equidigital number, since it uses as much as digits as its factorization.

661452250021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 28800, while the sum is 34.

The spelling of 661452250021 in words is "six hundred sixty-one billion, four hundred fifty-two million, two hundred fifty thousand, twenty-one".