649949681 has 2 divisors, whose sum is σ = 649949682. Its totient is φ = 649949680.

The previous prime is 649949639. The next prime is 649949731. The reversal of 649949681 is 186949946.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 632975281 + 16974400 = 25159^2 + 4120^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-649949681 is a prime.

It is a super-2 number, since 2×649949681² = 844869175664003522, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (649949621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 324974840 + 324974841.

It is an arithmetic number, because the mean of its divisors is an integer number (324974841).

Almost surely, 2^649949681 is an apocalyptic number.

It is an amenable number.

649949681 is a deficient number, since it is larger than the sum of its proper divisors (1).

649949681 is an equidigital number, since it uses as much as digits as its factorization.

649949681 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3359232, while the sum is 56.

The square root of 649949681 is about 25494.1107120841. The cubic root of 649949681 is about 866.2167517971.

The spelling of 649949681 in words is "six hundred forty-nine million, nine hundred forty-nine thousand, six hundred eighty-one".