155406121 has 4 divisors (see below), whose sum is σ = 167360452. Its totient is φ = 143451792.

The previous prime is 155406103. The next prime is 155406127. The reversal of 155406121 is 121604551.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 26265625 + 129140496 = 5125^2 + 11364^2 .

It is a cyclic number.

It is not a de Polignac number, because 155406121 - 2⁹ = 155405609 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (155406127) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5977146 + ... + 5977171.

It is an arithmetic number, because the mean of its divisors is an integer number (41840113).

Almost surely, 2^155406121 is an apocalyptic number.

It is an amenable number.

155406121 is a deficient number, since it is larger than the sum of its proper divisors (11954331).

155406121 is a wasteful number, since it uses less digits than its factorization.

155406121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11954330.

The product of its (nonzero) digits is 1200, while the sum is 25.

The square root of 155406121 is about 12466.1991400747. The cubic root of 155406121 is about 537.6372777900.

The spelling of 155406121 in words is "one hundred fifty-five million, four hundred six thousand, one hundred twenty-one".