2000021001991 has 2 divisors, whose sum is σ = 2000021001992. Its totient is φ = 2000021001990.

The previous prime is 2000021001833. The next prime is 2000021002019. The reversal of 2000021001991 is 1991001200002.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 2000021001991 - 2¹⁹ = 2000020477703 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2000021001091) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1000010500995 + 1000010500996.

It is an arithmetic number, because the mean of its divisors is an integer number (1000010500996).

Almost surely, 2^{2000021001991} is an apocalyptic number.

2000021001991 is a deficient number, since it is larger than the sum of its proper divisors (1).

2000021001991 is an equidigital number, since it uses as much as digits as its factorization.

2000021001991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 324, while the sum is 25.

Adding to 2000021001991 its reverse (1991001200002), we get a palindrome (3991022201993).

The spelling of 2000021001991 in words is "two trillion, twenty-one million, one thousand, nine hundred ninety-one".