649986581 has 8 divisors (see below), whose sum is σ = 666214560. Its totient is φ = 633809232.

The previous prime is 649986577. The next prime is 649986613. The reversal of 649986581 is 185689946.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 649986581 - 2² = 649986577 is a prime.

It is a super-2 number, since 2×649986581² = 844965110960139122, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (649989581) 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 in 7 ways as a sum of consecutive naturals, for example, 14030 + ... + 38688.

It is an arithmetic number, because the mean of its divisors is an integer number (83276820).

Almost surely, 2^649986581 is an apocalyptic number.

It is an amenable number.

649986581 is a deficient number, since it is larger than the sum of its proper divisors (16227979).

649986581 is a wasteful number, since it uses less digits than its factorization.

649986581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25315.

The product of its digits is 3732480, while the sum is 56.

The square root of 649986581 is about 25494.8343983639. The cubic root of 649986581 is about 866.2331442422.

It can be divided in two parts, 6499865 and 81, that added together give a palindrome (6499946).

The spelling of 649986581 in words is "six hundred forty-nine million, nine hundred eighty-six thousand, five hundred eighty-one".