646855823 has 4 divisors (see below), whose sum is σ = 650595048. Its totient is φ = 643116600.

The previous prime is 646855819. The next prime is 646855879. The reversal of 646855823 is 328558646.

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

It is a cyclic number.

It is not a de Polignac number, because 646855823 - 2² = 646855819 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 (646855123) 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, 1869353 + ... + 1869698.

It is an arithmetic number, because the mean of its divisors is an integer number (162648762).

Almost surely, 2^646855823 is an apocalyptic number.

646855823 is a deficient number, since it is larger than the sum of its proper divisors (3739225).

646855823 is a wasteful number, since it uses less digits than its factorization.

646855823 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3739224.

The product of its digits is 1382400, while the sum is 47.

The square root of 646855823 is about 25433.3604346732. The cubic root of 646855823 is about 864.8401245951.

The spelling of 646855823 in words is "six hundred forty-six million, eight hundred fifty-five thousand, eight hundred twenty-three".