2131091821 has 2 divisors, whose sum is σ = 2131091822. Its totient is φ = 2131091820.

The previous prime is 2131091803. The next prime is 2131091827. The reversal of 2131091821 is 1281901312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1145822500 + 985269321 = 33850^2 + 31389^2 .

It is a cyclic number.

It is not a de Polignac number, because 2131091821 - 2⁷ = 2131091693 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 2131091821.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2131091827) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1065545910 + 1065545911.

It is an arithmetic number, because the mean of its divisors is an integer number (1065545911).

Almost surely, 2^2131091821 is an apocalyptic number.

It is an amenable number.

2131091821 is a deficient number, since it is larger than the sum of its proper divisors (1).

2131091821 is an equidigital number, since it uses as much as digits as its factorization.

2131091821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 864, while the sum is 28.

The square root of 2131091821 is about 46163.7500751401. The cubic root of 2131091821 is about 1286.8681555633.

The spelling of 2131091821 in words is "two billion, one hundred thirty-one million, ninety-one thousand, eight hundred twenty-one".