649431581 has 2 divisors, whose sum is σ = 649431582. Its totient is φ = 649431580.

The previous prime is 649431529. The next prime is 649431641. The reversal of 649431581 is 185134946.

649431581 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 639634681 + 9796900 = 25291^2 + 3130^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-649431581 is a prime.

It is a super-2 number, since 2×649431581² = 843522756800319122, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (649421581) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 324715790 + 324715791.

It is an arithmetic number, because the mean of its divisors is an integer number (324715791).

Almost surely, 2^649431581 is an apocalyptic number.

It is an amenable number.

649431581 is a deficient number, since it is larger than the sum of its proper divisors (1).

649431581 is an equidigital number, since it uses as much as digits as its factorization.

649431581 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 103680, while the sum is 41.

The square root of 649431581 is about 25483.9475160345. The cubic root of 649431581 is about 865.9865256665.

The spelling of 649431581 in words is "six hundred forty-nine million, four hundred thirty-one thousand, five hundred eighty-one".