649791081 has 27 divisors (see below), whose sum is σ = 975397189. Its totient is φ = 416828832.

The previous prime is 649791067. The next prime is 649791091. The reversal of 649791081 is 180197946.

It is a happy number.

The square root of 649791081 is 25491.

It is a perfect power (a square), and thus also a powerful number.

649791081 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 192515625 + 457275456 = 13875^2 + 21384^2 .

It is not a de Polignac number, because 649791081 - 2⁹ = 649790569 is a prime.

It is a super-2 number, since 2×649791081² = 844456897894297122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (649791011) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 2217571 + ... + 2217863.

Almost surely, 2^649791081 is an apocalyptic number.

649791081 is the 25491-st square number.

649791081 is the 12746-th centered octagonal number.

It is an amenable number.

649791081 is a deficient number, since it is larger than the sum of its proper divisors (325606108).

649791081 is an equidigital number, since it uses as much as digits as its factorization.

649791081 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 650 (or 325 counting only the distinct ones).

The product of its (nonzero) digits is 108864, while the sum is 45.

The cubic root of 649791081 is about 866.1462883151.

The spelling of 649791081 in words is "six hundred forty-nine million, seven hundred ninety-one thousand, eighty-one".