649780813 has 4 divisors (see below), whose sum is σ = 708851808. Its totient is φ = 590709820.

The previous prime is 649780799. The next prime is 649780819. The reversal of 649780813 is 318087946.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 649780813 - 2⁹ = 649780301 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (649780819) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 29535481 + ... + 29535502.

It is an arithmetic number, because the mean of its divisors is an integer number (177212952).

Almost surely, 2^649780813 is an apocalyptic number.

It is an amenable number.

649780813 is a deficient number, since it is larger than the sum of its proper divisors (59070995).

649780813 is a wasteful number, since it uses less digits than its factorization.

649780813 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 59070994.

The product of its (nonzero) digits is 290304, while the sum is 46.

The square root of 649780813 is about 25490.7985947871. The cubic root of 649780813 is about 866.1417260093.

The spelling of 649780813 in words is "six hundred forty-nine million, seven hundred eighty thousand, eight hundred thirteen".