221212131 has 16 divisors (see below), whose sum is σ = 339322368. Its totient is φ = 125568000.

The previous prime is 221212129. The next prime is 221212133. The reversal of 221212131 is 131212122.

It is an interprime number because it is at equal distance from previous prime (221212129) and next prime (221212133).

It is not a de Polignac number, because 221212131 - 2¹ = 221212129 is a prime.

It is a super-2 number, since 2×221212131² = 97869613803122322, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 221212131.

It is not an unprimeable number, because it can be changed into a prime (221212133) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 31710 + ... + 38051.

It is an arithmetic number, because the mean of its divisors is an integer number (21207648).

Almost surely, 2^221212131 is an apocalyptic number.

221212131 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

221212131 is a deficient number, since it is larger than the sum of its proper divisors (118110237).

221212131 is a wasteful number, since it uses less digits than its factorization.

221212131 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 69922.

The product of its digits is 48, while the sum is 15.

The square root of 221212131 is about 14873.2017736599. The cubic root of 221212131 is about 604.7877414905.

Adding to 221212131 its reverse (131212122), we get a palindrome (352424253).

Subtracting from 221212131 its reverse (131212122), we obtain a palindrome (90000009).

The spelling of 221212131 in words is "two hundred twenty-one million, two hundred twelve thousand, one hundred thirty-one".