351216221 has 4 divisors (see below), whose sum is σ = 351281952. Its totient is φ = 351150492.

The previous prime is 351216199. The next prime is 351216253. The reversal of 351216221 is 122612153.

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.

It is a cyclic number.

It is not a de Polignac number, because 351216221 - 2¹⁸ = 350954077 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 (351213221) 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, 24065 + ... + 35798.

It is an arithmetic number, because the mean of its divisors is an integer number (87820488).

Almost surely, 2^351216221 is an apocalyptic number.

It is an amenable number.

351216221 is a deficient number, since it is larger than the sum of its proper divisors (65731).

351216221 is an equidigital number, since it uses as much as digits as its factorization.

351216221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 65730.

The product of its digits is 720, while the sum is 23.

The square root of 351216221 is about 18740.7636183801. The cubic root of 351216221 is about 705.5452221503.

Adding to 351216221 its reverse (122612153), we get a palindrome (473828374).

The spelling of 351216221 in words is "three hundred fifty-one million, two hundred sixteen thousand, two hundred twenty-one".