135906021 has 24 divisors (see below), whose sum is σ = 203223384. Its totient is φ = 87459840.

The previous prime is 135906019. The next prime is 135906049. The reversal of 135906021 is 120609531.

135906021 is a `hidden beast` number, since 1 + 3 + 59 + 0 + 602 + 1 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 8328996 + 127577025 = 2886^2 + 11295^2 .

It is not a de Polignac number, because 135906021 - 2¹ = 135906019 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (135906061) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 33895 + ... + 37691.

It is an arithmetic number, because the mean of its divisors is an integer number (8467641).

Almost surely, 2^135906021 is an apocalyptic number.

It is an amenable number.

135906021 is a deficient number, since it is larger than the sum of its proper divisors (67317363).

135906021 is a wasteful number, since it uses less digits than its factorization.

135906021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3941 (or 3938 counting only the distinct ones).

The product of its (nonzero) digits is 1620, while the sum is 27.

The square root of 135906021 is about 11657.8737769801. The cubic root of 135906021 is about 514.1378366831.

The spelling of 135906021 in words is "one hundred thirty-five million, nine hundred six thousand, twenty-one".