100131221 has 4 divisors (see below), whose sum is σ = 101017452. Its totient is φ = 99244992.

The previous prime is 100131211. The next prime is 100131223. The reversal of 100131221 is 122131001.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 122131001 = 2069 ⋅59029.

It can be written as a sum of positive squares in 2 ways, for example, as 18879025 + 81252196 = 4345^2 + 9014^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-100131221 is a prime.

It is a super-2 number, since 2×100131221² = 20052522837901682, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (100131223) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 442946 + ... + 443171.

It is an arithmetic number, because the mean of its divisors is an integer number (25254363).

Almost surely, 2^100131221 is an apocalyptic number.

It is an amenable number.

100131221 is a deficient number, since it is larger than the sum of its proper divisors (886231).

100131221 is an equidigital number, since it uses as much as digits as its factorization.

100131221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 886230.

The product of its (nonzero) digits is 12, while the sum is 11.

The square root of 100131221 is about 10006.5588990422. The cubic root of 100131221 is about 464.3618192651.

Adding to 100131221 its reverse (122131001), we get a palindrome (222262222).

The spelling of 100131221 in words is "one hundred million, one hundred thirty-one thousand, two hundred twenty-one".