221212123655 has 4 divisors (see below), whose sum is σ = 265454548392. Its totient is φ = 176969698920.

The previous prime is 221212123633. The next prime is 221212123673. The reversal of 221212123655 is 556321212122.

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

It is not a de Polignac number, because 221212123655 - 2²⁶ = 221145014791 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 22121212361 + ... + 22121212370.

It is an arithmetic number, because the mean of its divisors is an integer number (66363637098).

Almost surely, 2^221212123655 is an apocalyptic number.

221212123655 is a deficient number, since it is larger than the sum of its proper divisors (44242424737).

221212123655 is an equidigital number, since it uses as much as digits as its factorization.

221212123655 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 44242424736.

The product of its digits is 14400, while the sum is 32.

Adding to 221212123655 its reverse (556321212122), we get a palindrome (777533335777).

The spelling of 221212123655 in words is "two hundred twenty-one billion, two hundred twelve million, one hundred twenty-three thousand, six hundred fifty-five".