646342861 has 4 divisors (see below), whose sum is σ = 647080732. Its totient is φ = 645604992.

The previous prime is 646342811. The next prime is 646342871. The reversal of 646342861 is 168243646.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 168243646 = 2 ⋅84121823.

It can be written as a sum of positive squares in 2 ways, for example, as 424154025 + 222188836 = 20595^2 + 14906^2 .

It is a cyclic number.

It is not a de Polignac number, because 646342861 - 2²⁹ = 109471949 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 (646342811) 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, 367620 + ... + 369373.

It is an arithmetic number, because the mean of its divisors is an integer number (161770183).

Almost surely, 2^646342861 is an apocalyptic number.

It is an amenable number.

646342861 is a deficient number, since it is larger than the sum of its proper divisors (737871).

646342861 is an equidigital number, since it uses as much as digits as its factorization.

646342861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 737870.

The product of its digits is 165888, while the sum is 40.

The square root of 646342861 is about 25423.2740023782. The cubic root of 646342861 is about 864.6114556896.

The spelling of 646342861 in words is "six hundred forty-six million, three hundred forty-two thousand, eight hundred sixty-one".