1991012200221 has 16 divisors (see below), whose sum is σ = 2903908819968. Its totient is φ = 1203386113200.

The previous prime is 1991012200211. The next prime is 1991012200231. The reversal of 1991012200221 is 1220022101991.

It is an interprime number because it is at equal distance from previous prime (1991012200211) and next prime (1991012200231).

It is not a de Polignac number, because 1991012200221 - 2¹⁴ = 1991012183837 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1991012200211) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 82186395 + ... + 82210616.

It is an arithmetic number, because the mean of its divisors is an integer number (181494301248).

Almost surely, 2^{1991012200221} is an apocalyptic number.

1991012200221 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1991012200221 is a deficient number, since it is larger than the sum of its proper divisors (912896619747).

1991012200221 is a wasteful number, since it uses less digits than its factorization.

1991012200221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 164397392.

The product of its (nonzero) digits is 1296, while the sum is 30.

The spelling of 1991012200221 in words is "one trillion, nine hundred ninety-one billion, twelve million, two hundred thousand, two hundred twenty-one".