136663781 has 2 divisors, whose sum is σ = 136663782. Its totient is φ = 136663780.

The previous prime is 136663763. The next prime is 136663819. The reversal of 136663781 is 187366631.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 80263681 + 56400100 = 8959^2 + 7510^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-136663781 is a prime.

It is a super-2 number, since 2×136663781² = 37353978074431922, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (136663721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 68331890 + 68331891.

It is an arithmetic number, because the mean of its divisors is an integer number (68331891).

Almost surely, 2^136663781 is an apocalyptic number.

It is an amenable number.

136663781 is a deficient number, since it is larger than the sum of its proper divisors (1).

136663781 is an equidigital number, since it uses as much as digits as its factorization.

136663781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 108864, while the sum is 41.

The square root of 136663781 is about 11690.3285240407. The cubic root of 136663781 is about 515.0916115657.

The spelling of 136663781 in words is "one hundred thirty-six million, six hundred sixty-three thousand, seven hundred eighty-one".