55515121221 has 8 divisors (see below), whose sum is σ = 84594470464. Its totient is φ = 31722926400.

The previous prime is 55515121219. The next prime is 55515121241. The reversal of 55515121221 is 12212151555.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 55515121221 - 2¹ = 55515121219 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (55515121241) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1321788580 + ... + 1321788621.

It is an arithmetic number, because the mean of its divisors is an integer number (10574308808).

Almost surely, 2^55515121221 is an apocalyptic number.

It is an amenable number.

55515121221 is a deficient number, since it is larger than the sum of its proper divisors (29079349243).

55515121221 is a wasteful number, since it uses less digits than its factorization.

55515121221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2643577211.

The product of its digits is 5000, while the sum is 30.

Adding to 55515121221 its reverse (12212151555), we get a palindrome (67727272776).

The spelling of 55515121221 in words is "fifty-five billion, five hundred fifteen million, one hundred twenty-one thousand, two hundred twenty-one".