646971810101 has 4 divisors (see below), whose sum is σ = 646974302892. Its totient is φ = 646969317312.

The previous prime is 646971810073. The next prime is 646971810103. The reversal of 646971810101 is 101018179646.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 101018179646 = 2 ⋅50509089823.

It can be written as a sum of positive squares in 2 ways, for example, as 307547884900 + 339423925201 = 554570^2 + 582601^2 .

It is a cyclic number.

It is not a de Polignac number, because 646971810101 - 2²⁶ = 646904701237 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 (646971810103) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 804980 + ... + 1393533.

It is an arithmetic number, because the mean of its divisors is an integer number (161743575723).

Almost surely, 2^646971810101 is an apocalyptic number.

It is an amenable number.

646971810101 is a deficient number, since it is larger than the sum of its proper divisors (2492791).

646971810101 is a wasteful number, since it uses less digits than its factorization.

646971810101 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2492790.

The product of its (nonzero) digits is 72576, while the sum is 44.

Adding to 646971810101 its reverse (101018179646), we get a palindrome (747989989747).

The spelling of 646971810101 in words is "six hundred forty-six billion, nine hundred seventy-one million, eight hundred ten thousand, one hundred one".