133681815781 has 2 divisors, whose sum is σ = 133681815782. Its totient is φ = 133681815780.

The previous prime is 133681815769. The next prime is 133681815833. The reversal of 133681815781 is 187518186331.

It is an a-pointer prime, because the next prime (133681815833) can be obtained adding 133681815781 to its sum of digits (52).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 96944426881 + 36737388900 = 311359^2 + 191670^2 .

It is a cyclic number.

It is not a de Polignac number, because 133681815781 - 2²¹ = 133679718629 is a prime.

It is a super-2 number, since 2×133681815781² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (133681813781) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 66840907890 + 66840907891.

It is an arithmetic number, because the mean of its divisors is an integer number (66840907891).

Almost surely, 2^133681815781 is an apocalyptic number.

It is an amenable number.

133681815781 is a deficient number, since it is larger than the sum of its proper divisors (1).

133681815781 is an equidigital number, since it uses as much as digits as its factorization.

133681815781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 967680, while the sum is 52.

The spelling of 133681815781 in words is "one hundred thirty-three billion, six hundred eighty-one million, eight hundred fifteen thousand, seven hundred eighty-one".