55518121 has 4 divisors (see below), whose sum is σ = 55553872. Its totient is φ = 55482372.

The previous prime is 55518101. The next prime is 55518137. The reversal of 55518121 is 12181555.

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: 12181555 = 5 ⋅2436311.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-55518121 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 55518121.

It is not an unprimeable number, because it can be changed into a prime (55518101) 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, 15435 + ... + 18688.

It is an arithmetic number, because the mean of its divisors is an integer number (13888468).

Almost surely, 2^55518121 is an apocalyptic number.

It is an amenable number.

55518121 is a deficient number, since it is larger than the sum of its proper divisors (35751).

55518121 is a wasteful number, since it uses less digits than its factorization.

55518121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35750.

The product of its digits is 2000, while the sum is 28.

The square root of 55518121 is about 7451.0483155057. The cubic root of 55518121 is about 381.4856911897.

Adding to 55518121 its reverse (12181555), we get a palindrome (67699676).

The spelling of 55518121 in words is "fifty-five million, five hundred eighteen thousand, one hundred twenty-one".