135121561 has 2 divisors, whose sum is σ = 135121562. Its totient is φ = 135121560.

The previous prime is 135121549. The next prime is 135121603. The reversal of 135121561 is 165121531.

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., 67963536 + 67158025 = 8244^2 + 8195^2 .

It is a cyclic number.

It is not a de Polignac number, because 135121561 - 2¹³ = 135113369 is a prime.

It is not a weakly prime, because it can be changed into another prime (135121501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 67560780 + 67560781.

It is an arithmetic number, because the mean of its divisors is an integer number (67560781).

Almost surely, 2^135121561 is an apocalyptic number.

It is an amenable number.

135121561 is a deficient number, since it is larger than the sum of its proper divisors (1).

135121561 is an equidigital number, since it uses as much as digits as its factorization.

135121561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 900, while the sum is 25.

The square root of 135121561 is about 11624.1800140913. The cubic root of 135121561 is about 513.1467129112.

The spelling of 135121561 in words is "one hundred thirty-five million, one hundred twenty-one thousand, five hundred sixty-one".