208281979681 has 4 divisors (see below), whose sum is σ = 217337717952. Its totient is φ = 199226241412.

The previous prime is 208281979673. The next prime is 208281979687. The reversal of 208281979681 is 186979182802.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 208281979681 - 2³ = 208281979673 is a prime.

It is a super-2 number, since 2×208281979681² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (208281979687) 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, 4527869101 + ... + 4527869146.

It is an arithmetic number, because the mean of its divisors is an integer number (54334429488).

Almost surely, 2^208281979681 is an apocalyptic number.

It is an amenable number.

208281979681 is a deficient number, since it is larger than the sum of its proper divisors (9055738271).

208281979681 is an equidigital number, since it uses as much as digits as its factorization.

208281979681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9055738270.

The product of its (nonzero) digits is 6967296, while the sum is 61.

The spelling of 208281979681 in words is "two hundred eight billion, two hundred eighty-one million, nine hundred seventy-nine thousand, six hundred eighty-one".