649689818 has 4 divisors (see below), whose sum is σ = 974534730. Its totient is φ = 324844908.

The previous prime is 649689811. The next prime is 649689829. The reversal of 649689818 is 818986946.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 818986946 = 2 ⋅409493473.

It can be written as a sum of positive squares in only one way, i.e., 619362769 + 30327049 = 24887^2 + 5507^2 .

It is a super-2 number, since 2×649689818² = 844193719225746248, which contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (649689811) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 162422453 + ... + 162422456.

Almost surely, 2^649689818 is an apocalyptic number.

649689818 is a deficient number, since it is larger than the sum of its proper divisors (324844912).

649689818 is a wasteful number, since it uses less digits than its factorization.

649689818 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 324844911.

The product of its digits is 5971968, while the sum is 59.

The square root of 649689818 is about 25489.0136725610. The cubic root of 649689818 is about 866.1012927616.

The spelling of 649689818 in words is "six hundred forty-nine million, six hundred eighty-nine thousand, eight hundred eighteen".