208137281609 has 2 divisors, whose sum is σ = 208137281610. Its totient is φ = 208137281608.

The previous prime is 208137281503. The next prime is 208137281663. The reversal of 208137281609 is 906182731802.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 107143619584 + 100993662025 = 327328^2 + 317795^2 .

It is a cyclic number.

It is not a de Polignac number, because 208137281609 - 2⁸ = 208137281353 is a prime.

It is a super-2 number, since 2×208137281609² (a number of 23 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (208137281689) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104068640804 + 104068640805.

It is an arithmetic number, because the mean of its divisors is an integer number (104068640805).

Almost surely, 2^208137281609 is an apocalyptic number.

It is an amenable number.

208137281609 is a deficient number, since it is larger than the sum of its proper divisors (1).

208137281609 is an equidigital number, since it uses as much as digits as its factorization.

208137281609 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 290304, while the sum is 47.

The spelling of 208137281609 in words is "two hundred eight billion, one hundred thirty-seven million, two hundred eighty-one thousand, six hundred nine".