646863841 has 4 divisors (see below), whose sum is σ = 696622612. Its totient is φ = 597105072.

The previous prime is 646863829. The next prime is 646863851. The reversal of 646863841 is 148368646.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 74649600 + 572214241 = 8640^2 + 23921^2 .

It is a cyclic number.

It is not a de Polignac number, because 646863841 - 2⁵ = 646863809 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 646863791 and 646863800.

It is not an unprimeable number, because it can be changed into a prime (646863851) 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, 24879366 + ... + 24879391.

It is an arithmetic number, because the mean of its divisors is an integer number (174155653).

Almost surely, 2^646863841 is an apocalyptic number.

It is an amenable number.

646863841 is a deficient number, since it is larger than the sum of its proper divisors (49758771).

646863841 is a wasteful number, since it uses less digits than its factorization.

646863841 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 49758770.

The product of its digits is 663552, while the sum is 46.

The square root of 646863841 is about 25433.5180618018. The cubic root of 646863841 is about 864.8436979104.

The spelling of 646863841 in words is "six hundred forty-six million, eight hundred sixty-three thousand, eight hundred forty-one".