19730891 has 2 divisors, whose sum is σ = 19730892. Its totient is φ = 19730890.

The previous prime is 19730857. The next prime is 19730899. The reversal of 19730891 is 19803791.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 19730891 - 2¹⁰ = 19729867 is a prime.

It is not a weakly prime, because it can be changed into another prime (19730899) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9865445 + 9865446.

It is an arithmetic number, because the mean of its divisors is an integer number (9865446).

Almost surely, 2^19730891 is an apocalyptic number.

19730891 is a deficient number, since it is larger than the sum of its proper divisors (1).

19730891 is an equidigital number, since it uses as much as digits as its factorization.

19730891 is an evil number, because the sum of its binary digits is even.

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

The square root of 19730891 is about 4441.9467578979. The cubic root of 19730891 is about 270.2188029766.

Subtracting 19730891 from its reverse (19803791), we obtain a square (72900 = 270²).

It can be divided in two parts, 197308 and 91, that multiplied together give a triangular number (17955028 = T₅₉₉₂).

The spelling of 19730891 in words is "nineteen million, seven hundred thirty thousand, eight hundred ninety-one".