135521055661 has 2 divisors, whose sum is σ = 135521055662. Its totient is φ = 135521055660.

The previous prime is 135521055623. The next prime is 135521055721. The reversal of 135521055661 is 166550125531.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 127498270761 + 8022784900 = 357069^2 + 89570^2 .

It is a cyclic number.

It is not a de Polignac number, because 135521055661 - 2⁷ = 135521055533 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (135521055611) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 67760527830 + 67760527831.

It is an arithmetic number, because the mean of its divisors is an integer number (67760527831).

Almost surely, 2^135521055661 is an apocalyptic number.

It is an amenable number.

135521055661 is a deficient number, since it is larger than the sum of its proper divisors (1).

135521055661 is an equidigital number, since it uses as much as digits as its factorization.

135521055661 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 135000, while the sum is 40.

The spelling of 135521055661 in words is "one hundred thirty-five billion, five hundred twenty-one million, fifty-five thousand, six hundred sixty-one".