646513849 has 4 divisors (see below), whose sum is σ = 668807460. Its totient is φ = 624220240.

The previous prime is 646513843. The next prime is 646513853. The reversal of 646513849 is 948315646.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 948315646 = 2 ⋅474157823.

It can be written as a sum of positive squares in 2 ways, for example, as 306775225 + 339738624 = 17515^2 + 18432^2 .

It is a cyclic number.

It is not a de Polignac number, because 646513849 - 2⁹ = 646513337 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 646513799 and 646513808.

It is not an unprimeable number, because it can be changed into a prime (646513843) 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, 11146762 + ... + 11146819.

It is an arithmetic number, because the mean of its divisors is an integer number (167201865).

Almost surely, 2^646513849 is an apocalyptic number.

It is an amenable number.

646513849 is a deficient number, since it is larger than the sum of its proper divisors (22293611).

646513849 is a wasteful number, since it uses less digits than its factorization.

646513849 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22293610.

The product of its digits is 622080, while the sum is 46.

The square root of 646513849 is about 25426.6366041598. The cubic root of 646513849 is about 864.6876923940.

The spelling of 646513849 in words is "six hundred forty-six million, five hundred thirteen thousand, eight hundred forty-nine".