131223991 has 2 divisors, whose sum is σ = 131223992. Its totient is φ = 131223990.

The previous prime is 131223973. The next prime is 131224007. The reversal of 131223991 is 199322131.

It is a strong prime.

It is an emirp because it is prime and its reverse (199322131) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 131223991 - 2¹⁷ = 131092919 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (131223931) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 65611995 + 65611996.

It is an arithmetic number, because the mean of its divisors is an integer number (65611996).

Almost surely, 2^131223991 is an apocalyptic number.

131223991 is a deficient number, since it is larger than the sum of its proper divisors (1).

131223991 is an equidigital number, since it uses as much as digits as its factorization.

131223991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2916, while the sum is 31.

The square root of 131223991 is about 11455.3040553274. The cubic root of 131223991 is about 508.1646073608.

The spelling of 131223991 in words is "one hundred thirty-one million, two hundred twenty-three thousand, nine hundred ninety-one".