649871604 has 18 divisors (see below), whose sum is σ = 1642731090. Its totient is φ = 216623856.

The previous prime is 649871587. The next prime is 649871609. The reversal of 649871604 is 406178946.

It can be written as a sum of positive squares in only one way, i.e., 452412900 + 197458704 = 21270^2 + 14052^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is a self number, because there is not a number n which added to its sum of digits gives 649871604.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (649871609) 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, 9025959 + ... + 9026030.

Almost surely, 2^649871604 is an apocalyptic number.

It is an amenable number.

649871604 is an abundant number, since it is smaller than the sum of its proper divisors (992859486).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

649871604 is a wasteful number, since it uses less digits than its factorization.

649871604 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18051999 (or 18051994 counting only the distinct ones).

The product of its (nonzero) digits is 290304, while the sum is 45.

The square root of 649871604 is about 25492.5793908737. The cubic root of 649871604 is about 866.1820648485.

The spelling of 649871604 in words is "six hundred forty-nine million, eight hundred seventy-one thousand, six hundred four".