2191804236437 has 2 divisors, whose sum is σ = 2191804236438. Its totient is φ = 2191804236436.

The previous prime is 2191804236379. The next prime is 2191804236449. The reversal of 2191804236437 is 7346324081912.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 2015531053636 + 176273182801 = 1419694^2 + 419849^2 .

It is a cyclic number.

It is not a de Polignac number, because 2191804236437 - 2⁶ = 2191804236373 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2191804236467) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1095902118218 + 1095902118219.

It is an arithmetic number, because the mean of its divisors is an integer number (1095902118219).

Almost surely, 2^{2191804236437} is an apocalyptic number.

It is an amenable number.

2191804236437 is a deficient number, since it is larger than the sum of its proper divisors (1).

2191804236437 is an equidigital number, since it uses as much as digits as its factorization.

2191804236437 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1741824, while the sum is 50.

The spelling of 2191804236437 in words is "two trillion, one hundred ninety-one billion, eight hundred four million, two hundred thirty-six thousand, four hundred thirty-seven".