221217131 has 2 divisors, whose sum is σ = 221217132. Its totient is φ = 221217130.

The previous prime is 221217127. The next prime is 221217149. The reversal of 221217131 is 131712122.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 221217131 - 2² = 221217127 is a prime.

It is a super-2 number, since 2×221217131² = 97874038095742322, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (221217331) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110608565 + 110608566.

It is an arithmetic number, because the mean of its divisors is an integer number (110608566).

Almost surely, 2^221217131 is an apocalyptic number.

221217131 is a deficient number, since it is larger than the sum of its proper divisors (1).

221217131 is an equidigital number, since it uses as much as digits as its factorization.

221217131 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 168, while the sum is 20.

The square root of 221217131 is about 14873.3698602570. The cubic root of 221217131 is about 604.7922980759.

Adding to 221217131 its reverse (131712122), we get a palindrome (352929253).

The spelling of 221217131 in words is "two hundred twenty-one million, two hundred seventeen thousand, one hundred thirty-one".