221216127551 has 4 divisors (see below), whose sum is σ = 221849985000. Its totient is φ = 220582270104.

The previous prime is 221216127521. The next prime is 221216127557. The reversal of 221216127551 is 155721612122.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221216127551 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221216127557) 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, 316928201 + ... + 316928898.

It is an arithmetic number, because the mean of its divisors is an integer number (55462496250).

Almost surely, 2^221216127551 is an apocalyptic number.

221216127551 is a deficient number, since it is larger than the sum of its proper divisors (633857449).

221216127551 is an equidigital number, since it uses as much as digits as its factorization.

221216127551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 633857448.

The product of its digits is 16800, while the sum is 35.

Adding to 221216127551 its reverse (155721612122), we get a palindrome (376937739673).

The spelling of 221216127551 in words is "two hundred twenty-one billion, two hundred sixteen million, one hundred twenty-seven thousand, five hundred fifty-one".