135538561 has 4 divisors (see below), whose sum is σ = 136226772. Its totient is φ = 134850352.

The previous prime is 135538499. The next prime is 135538567. The reversal of 135538561 is 165835531.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 165835531 = 227 ⋅730553.

It can be written as a sum of positive squares in 2 ways, for example, as 115691536 + 19847025 = 10756^2 + 4455^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-135538561 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 135538561.

It is not an unprimeable number, because it can be changed into a prime (135538567) 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, 343810 + ... + 344203.

It is an arithmetic number, because the mean of its divisors is an integer number (34056693).

Almost surely, 2^135538561 is an apocalyptic number.

It is an amenable number.

135538561 is a deficient number, since it is larger than the sum of its proper divisors (688211).

135538561 is an equidigital number, since it uses as much as digits as its factorization.

135538561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 688210.

The product of its digits is 54000, while the sum is 37.

The square root of 135538561 is about 11642.1029457740. The cubic root of 135538561 is about 513.6740465460.

The spelling of 135538561 in words is "one hundred thirty-five million, five hundred thirty-eight thousand, five hundred sixty-one".