2120211991 has 2 divisors, whose sum is σ = 2120211992. Its totient is φ = 2120211990.

The previous prime is 2120211959. The next prime is 2120212019. The reversal of 2120211991 is 1991120212.

It is an a-pointer prime, because the next prime (2120212019) can be obtained adding 2120211991 to its sum of digits (28).

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 2120211991 - 2⁵ = 2120211959 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2120211941) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1060105995 + 1060105996.

It is an arithmetic number, because the mean of its divisors is an integer number (1060105996).

Almost surely, 2^2120211991 is an apocalyptic number.

2120211991 is a deficient number, since it is larger than the sum of its proper divisors (1).

2120211991 is an equidigital number, since it uses as much as digits as its factorization.

2120211991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 648, while the sum is 28.

The square root of 2120211991 is about 46045.7597504917. The cubic root of 2120211991 is about 1284.6744755227.

The spelling of 2120211991 in words is "two billion, one hundred twenty million, two hundred eleven thousand, nine hundred ninety-one".