221212001 has 4 divisors (see below), whose sum is σ = 228347904. Its totient is φ = 214076100.

The previous prime is 221211989. The next prime is 221212009. The reversal of 221212001 is 100212122.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 100212122 = 2 ⋅50106061.

It is a cyclic number.

It is not a de Polignac number, because 221212001 - 2¹⁴ = 221195617 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (221212009) 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, 3567905 + ... + 3567966.

It is an arithmetic number, because the mean of its divisors is an integer number (57086976).

Almost surely, 2^221212001 is an apocalyptic number.

It is an amenable number.

221212001 is a deficient number, since it is larger than the sum of its proper divisors (7135903).

221212001 is an equidigital number, since it uses as much as digits as its factorization.

221212001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7135902.

The product of its (nonzero) digits is 16, while the sum is 11.

The square root of 221212001 is about 14873.1974033830. The cubic root of 221212001 is about 604.7876230183.

Adding to 221212001 its reverse (100212122), we get a palindrome (321424123).

The spelling of 221212001 in words is "two hundred twenty-one million, two hundred twelve thousand, one".