649681081 has 8 divisors (see below), whose sum is σ = 743624640. Its totient is φ = 556020528.

The previous prime is 649681009. The next prime is 649681099. The reversal of 649681081 is 180186946.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 649681081 - 2⁹ = 649680569 is a prime.

It is a super-2 number, since 2×649681081² = 844171014018657122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (649681001) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 65806 + ... + 75031.

It is an arithmetic number, because the mean of its divisors is an integer number (92953080).

Almost surely, 2^649681081 is an apocalyptic number.

It is an amenable number.

649681081 is a deficient number, since it is larger than the sum of its proper divisors (93943559).

649681081 is a wasteful number, since it uses less digits than its factorization.

649681081 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 141503.

The product of its (nonzero) digits is 82944, while the sum is 43.

The square root of 649681081 is about 25488.8422844193. The cubic root of 649681081 is about 866.0974103135.

It can be divided in two parts, 64968 and 1081, that added together give a square (66049 = 257²).

The spelling of 649681081 in words is "six hundred forty-nine million, six hundred eighty-one thousand, eighty-one".