2145121691 has 2 divisors, whose sum is σ = 2145121692. Its totient is φ = 2145121690.

The previous prime is 2145121673. The next prime is 2145121697. The reversal of 2145121691 is 1961215412.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 2145121691 - 2¹⁴ = 2145105307 is a prime.

It is not a weakly prime, because it can be changed into another prime (2145121697) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1072560845 + 1072560846.

It is an arithmetic number, because the mean of its divisors is an integer number (1072560846).

Almost surely, 2^2145121691 is an apocalyptic number.

2145121691 is a deficient number, since it is larger than the sum of its proper divisors (1).

2145121691 is an equidigital number, since it uses as much as digits as its factorization.

2145121691 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4320, while the sum is 32.

The square root of 2145121691 is about 46315.4584453182. The cubic root of 2145121691 is about 1289.6859782889.

The spelling of 2145121691 in words is "two billion, one hundred forty-five million, one hundred twenty-one thousand, six hundred ninety-one".