221220212121 has 24 divisors (see below), whose sum is σ = 336388416000. Its totient is φ = 139705484832.

The previous prime is 221220212119. The next prime is 221220212123. The reversal of 221220212121 is 121212022122.

It is a happy number.

221220212121 is a `hidden beast` number, since 221 + 220 + 212 + 12 + 1 = 666.

It is an interprime number because it is at equal distance from previous prime (221220212119) and next prime (221220212123).

It is not a de Polignac number, because 221220212121 - 2¹ = 221220212119 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 221220212094 and 221220212103.

It is not an unprimeable number, because it can be changed into a prime (221220212123) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2082075 + ... + 2185743.

It is an arithmetic number, because the mean of its divisors is an integer number (14016184000).

Almost surely, 2^221220212121 is an apocalyptic number.

It is an amenable number.

221220212121 is a deficient number, since it is larger than the sum of its proper divisors (115168203879).

221220212121 is a wasteful number, since it uses less digits than its factorization.

221220212121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 116173 (or 116170 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 18.

Adding to 221220212121 its reverse (121212022122), we get a palindrome (342432234243).

The spelling of 221220212121 in words is "two hundred twenty-one billion, two hundred twenty million, two hundred twelve thousand, one hundred twenty-one".