131221643 has 4 divisors (see below), whose sum is σ = 149967600. Its totient is φ = 112475688.

The previous prime is 131221637. The next prime is 131221669. The reversal of 131221643 is 346122131.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 346122131 = 569 ⋅608299.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-131221643 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (131221613) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9372968 + ... + 9372981.

It is an arithmetic number, because the mean of its divisors is an integer number (37491900).

Almost surely, 2^131221643 is an apocalyptic number.

131221643 is a deficient number, since it is larger than the sum of its proper divisors (18745957).

131221643 is an equidigital number, since it uses as much as digits as its factorization.

131221643 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18745956.

The product of its digits is 864, while the sum is 23.

The square root of 131221643 is about 11455.2015695927. The cubic root of 131221643 is about 508.1615764678.

Adding to 131221643 its reverse (346122131), we get a palindrome (477343774).

The spelling of 131221643 in words is "one hundred thirty-one million, two hundred twenty-one thousand, six hundred forty-three".