648623681 has 2 divisors, whose sum is σ = 648623682. Its totient is φ = 648623680.

The previous prime is 648623663. The next prime is 648623683. The reversal of 648623681 is 186326846.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 354192400 + 294431281 = 18820^2 + 17159^2 .

It is a cyclic number.

It is not a de Polignac number, because 648623681 - 2⁶ = 648623617 is a prime.

It is a super-2 number, since 2×648623681² = 841425359107979522, which contains 22 as substring.

Together with 648623683, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (648623683) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 324311840 + 324311841.

It is an arithmetic number, because the mean of its divisors is an integer number (324311841).

Almost surely, 2^648623681 is an apocalyptic number.

It is an amenable number.

648623681 is a deficient number, since it is larger than the sum of its proper divisors (1).

648623681 is an equidigital number, since it uses as much as digits as its factorization.

648623681 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 331776, while the sum is 44.

The square root of 648623681 is about 25468.0914282951. The cubic root of 648623681 is about 865.6272777482.

The spelling of 648623681 in words is "six hundred forty-eight million, six hundred twenty-three thousand, six hundred eighty-one".