20002120231991 has 2 divisors, whose sum is σ = 20002120231992. Its totient is φ = 20002120231990.

The previous prime is 20002120231987. The next prime is 20002120231999. The reversal of 20002120231991 is 19913202120002.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20002120231991 - 2² = 20002120231987 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20002120231999) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10001060115995 + 10001060115996.

It is an arithmetic number, because the mean of its divisors is an integer number (10001060115996).

Almost surely, 2^{20002120231991} is an apocalyptic number.

20002120231991 is a deficient number, since it is larger than the sum of its proper divisors (1).

20002120231991 is an equidigital number, since it uses as much as digits as its factorization.

20002120231991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3888, while the sum is 32.

Adding to 20002120231991 its reverse (19913202120002), we get a palindrome (39915322351993).

The spelling of 20002120231991 in words is "twenty trillion, two billion, one hundred twenty million, two hundred thirty-one thousand, nine hundred ninety-one".