648971993 has 2 divisors, whose sum is σ = 648971994. Its totient is φ = 648971992.

The previous prime is 648971989. The next prime is 648972007. The reversal of 648971993 is 399179846.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 624400144 + 24571849 = 24988^2 + 4957^2 .

It is a cyclic number.

It is not a de Polignac number, because 648971993 - 2² = 648971989 is a prime.

It is not a weakly prime, because it can be changed into another prime (648971963) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 324485996 + 324485997.

It is an arithmetic number, because the mean of its divisors is an integer number (324485997).

Almost surely, 2^648971993 is an apocalyptic number.

It is an amenable number.

648971993 is a deficient number, since it is larger than the sum of its proper divisors (1).

648971993 is an equidigital number, since it uses as much as digits as its factorization.

648971993 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2939328, while the sum is 56.

The square root of 648971993 is about 25474.9287143262. The cubic root of 648971993 is about 865.7821977853.

The spelling of 648971993 in words is "six hundred forty-eight million, nine hundred seventy-one thousand, nine hundred ninety-three".