639972198261 has 48 divisors (see below), whose sum is σ = 1027673749440. Its totient is φ = 380467676160.

The previous prime is 639972198227. The next prime is 639972198379. The reversal of 639972198261 is 162891279936.

639972198261 is a `hidden beast` number, since 6 + 399 + 7 + 219 + 8 + 26 + 1 = 666.

It is not a de Polignac number, because 639972198261 - 2⁶ = 639972198197 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (639972198221) 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 47 ways as a sum of consecutive naturals, for example, 36820005 + ... + 36837381.

It is an arithmetic number, because the mean of its divisors is an integer number (21409869780).

Almost surely, 2^639972198261 is an apocalyptic number.

It is an amenable number.

639972198261 is a deficient number, since it is larger than the sum of its proper divisors (387701551179).

639972198261 is a wasteful number, since it uses less digits than its factorization.

639972198261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24466 (or 24463 counting only the distinct ones).

The product of its digits is 17635968, while the sum is 63.

The spelling of 639972198261 in words is "six hundred thirty-nine billion, nine hundred seventy-two million, one hundred ninety-eight thousand, two hundred sixty-one".