649581605 has 4 divisors (see below), whose sum is σ = 779497932. Its totient is φ = 519665280.

The previous prime is 649581593. The next prime is 649581613. The reversal of 649581605 is 506185946.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 204118369 + 445463236 = 14287^2 + 21106^2 .

It is not a de Polignac number, because 649581605 - 2¹⁶ = 649516069 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 64958156 + ... + 64958165.

It is an arithmetic number, because the mean of its divisors is an integer number (194874483).

Almost surely, 2^649581605 is an apocalyptic number.

It is an amenable number.

649581605 is a deficient number, since it is larger than the sum of its proper divisors (129916327).

649581605 is a wasteful number, since it uses less digits than its factorization.

649581605 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 129916326.

The product of its (nonzero) digits is 259200, while the sum is 44.

The square root of 649581605 is about 25486.8908460801. The cubic root of 649581605 is about 866.0532038528.

The spelling of 649581605 in words is "six hundred forty-nine million, five hundred eighty-one thousand, six hundred five".