55615216221 has 16 divisors (see below), whose sum is σ = 83521585920. Its totient is φ = 36568908000.

The previous prime is 55615216213. The next prime is 55615216273. The reversal of 55615216221 is 12261251655.

55615216221 is a `hidden beast` number, since 5 + 5 + 6 + 1 + 5 + 21 + 622 + 1 = 666.

It is not a de Polignac number, because 55615216221 - 2³ = 55615216213 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (55615216021) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 14106405 + ... + 14110346.

It is an arithmetic number, because the mean of its divisors is an integer number (5220099120).

Almost surely, 2^55615216221 is an apocalyptic number.

It is an amenable number.

55615216221 is a deficient number, since it is larger than the sum of its proper divisors (27906369699).

55615216221 is a wasteful number, since it uses less digits than its factorization.

55615216221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28216833 (or 28216827 counting only the distinct ones).

The product of its digits is 36000, while the sum is 36.

Adding to 55615216221 its reverse (12261251655), we get a palindrome (67876467876).

The spelling of 55615216221 in words is "fifty-five billion, six hundred fifteen million, two hundred sixteen thousand, two hundred twenty-one".