1911394721 has 2 divisors, whose sum is σ = 1911394722. Its totient is φ = 1911394720.

The previous prime is 1911394673. The next prime is 1911394741. The reversal of 1911394721 is 1274931191.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1191009121 + 720385600 = 34511^2 + 26840^2 .

It is an emirp because it is prime and its reverse (1274931191) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1911394721 - 2²² = 1907200417 is a prime.

It is not a weakly prime, because it can be changed into another prime (1911394741) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 955697360 + 955697361.

It is an arithmetic number, because the mean of its divisors is an integer number (955697361).

Almost surely, 2^1911394721 is an apocalyptic number.

It is an amenable number.

1911394721 is a deficient number, since it is larger than the sum of its proper divisors (1).

1911394721 is an equidigital number, since it uses as much as digits as its factorization.

1911394721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 13608, while the sum is 38.

The square root of 1911394721 is about 43719.5004660392. The cubic root of 1911394721 is about 1241.0333739704.

The spelling of 1911394721 in words is "one billion, nine hundred eleven million, three hundred ninety-four thousand, seven hundred twenty-one".