221212110421 has 2 divisors, whose sum is σ = 221212110422. Its totient is φ = 221212110420.

The previous prime is 221212110401. The next prime is 221212110443. The reversal of 221212110421 is 124011212122.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 156253393521 + 64958716900 = 395289^2 + 254870^2 .

It is a cyclic number.

It is not a de Polignac number, because 221212110421 - 2¹³ = 221212102229 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221212110401) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110606055210 + 110606055211.

It is an arithmetic number, because the mean of its divisors is an integer number (110606055211).

Almost surely, 2^221212110421 is an apocalyptic number.

It is an amenable number.

221212110421 is a deficient number, since it is larger than the sum of its proper divisors (1).

221212110421 is an equidigital number, since it uses as much as digits as its factorization.

221212110421 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 128, while the sum is 19.

Adding to 221212110421 its reverse (124011212122), we get a palindrome (345223322543).

The spelling of 221212110421 in words is "two hundred twenty-one billion, two hundred twelve million, one hundred ten thousand, four hundred twenty-one".