12201551991 has 8 divisors (see below), whose sum is σ = 18076373360. Its totient is φ = 8134367976.

The previous prime is 12201551969. The next prime is 12201552019. The reversal of 12201551991 is 19915510221.

12201551991 is a `hidden beast` number, since 12 + 2 + 0 + 1 + 551 + 9 + 91 = 666.

It is not a de Polignac number, because 12201551991 - 2⁶ = 12201551927 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12201551941) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 225954640 + ... + 225954693.

It is an arithmetic number, because the mean of its divisors is an integer number (2259546670).

Almost surely, 2^12201551991 is an apocalyptic number.

12201551991 is a deficient number, since it is larger than the sum of its proper divisors (5874821369).

12201551991 is an equidigital number, since it uses as much as digits as its factorization.

12201551991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 451909342 (or 451909336 counting only the distinct ones).

The product of its (nonzero) digits is 8100, while the sum is 36.

The spelling of 12201551991 in words is "twelve billion, two hundred one million, five hundred fifty-one thousand, nine hundred ninety-one".