15555121 has 4 divisors (see below), whose sum is σ = 15916912. Its totient is φ = 15193332.

The previous prime is 15555109. The next prime is 15555139. The reversal of 15555121 is 12155551.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12155551 = 127 ⋅95713.

It is a cyclic number.

It is not a de Polignac number, because 15555121 - 2¹¹ = 15553073 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (15555151) 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, 180831 + ... + 180916.

It is an arithmetic number, because the mean of its divisors is an integer number (3979228).

Almost surely, 2^15555121 is an apocalyptic number.

It is an amenable number.

15555121 is a deficient number, since it is larger than the sum of its proper divisors (361791).

15555121 is an equidigital number, since it uses as much as digits as its factorization.

15555121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 361790.

The product of its digits is 1250, while the sum is 25.

The square root of 15555121 is about 3943.9980983768. The cubic root of 15555121 is about 249.6267550301.

The spelling of 15555121 in words is "fifteen million, five hundred fifty-five thousand, one hundred twenty-one".