1931221393 has 2 divisors, whose sum is σ = 1931221394. Its totient is φ = 1931221392.

The previous prime is 1931221379. The next prime is 1931221421. The reversal of 1931221393 is 3931221391.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1915987984 + 15233409 = 43772^2 + 3903^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1931221393 is a prime.

It is not a weakly prime, because it can be changed into another prime (1931221363) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 965610696 + 965610697.

It is an arithmetic number, because the mean of its divisors is an integer number (965610697).

Almost surely, 2^1931221393 is an apocalyptic number.

It is an amenable number.

1931221393 is a deficient number, since it is larger than the sum of its proper divisors (1).

1931221393 is an equidigital number, since it uses as much as digits as its factorization.

1931221393 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8748, while the sum is 34.

The square root of 1931221393 is about 43945.6640978379. The cubic root of 1931221393 is about 1245.3096530357.

The spelling of 1931221393 in words is "one billion, nine hundred thirty-one million, two hundred twenty-one thousand, three hundred ninety-three".