646633861 has 4 divisors (see below), whose sum is σ = 653899500. Its totient is φ = 639368224.

The previous prime is 646633829. The next prime is 646633873. The reversal of 646633861 is 168336646.

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 351000225 + 295633636 = 18735^2 + 17194^2 .

It is a cyclic number.

It is not a de Polignac number, because 646633861 - 2⁵ = 646633829 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 (646633261) 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, 3632686 + ... + 3632863.

It is an arithmetic number, because the mean of its divisors is an integer number (163474875).

Almost surely, 2^646633861 is an apocalyptic number.

It is an amenable number.

646633861 is a deficient number, since it is larger than the sum of its proper divisors (7265639).

646633861 is an equidigital number, since it uses as much as digits as its factorization.

646633861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7265638.

The product of its digits is 373248, while the sum is 43.

The square root of 646633861 is about 25428.9964607336. The cubic root of 646633861 is about 864.7411929127.

The spelling of 646633861 in words is "six hundred forty-six million, six hundred thirty-three thousand, eight hundred sixty-one".