649157861 has 6 divisors (see below), whose sum is σ = 713537286. Its totient is φ = 590143400.

The previous prime is 649157813. The next prime is 649157867. The reversal of 649157861 is 168751946.

It can be written as a sum of positive squares in only one way, i.e., 429940225 + 219217636 = 20735^2 + 14806^2 .

It is a de Polignac number, because none of the positive numbers 2^k-649157861 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (649157867) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 2682350 + ... + 2682591.

It is an arithmetic number, because the mean of its divisors is an integer number (118922881).

Almost surely, 2^649157861 is an apocalyptic number.

It is an amenable number.

649157861 is a deficient number, since it is larger than the sum of its proper divisors (64379425).

649157861 is a wasteful number, since it uses less digits than its factorization.

649157861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5364963 (or 5364952 counting only the distinct ones).

The product of its digits is 362880, while the sum is 47.

The square root of 649157861 is about 25478.5765104725. The cubic root of 649157861 is about 865.8648443129.

The spelling of 649157861 in words is "six hundred forty-nine million, one hundred fifty-seven thousand, eight hundred sixty-one".