19911953 has 2 divisors, whose sum is σ = 19911954. Its totient is φ = 19911952.

The previous prime is 19911923. The next prime is 19911959. The reversal of 19911953 is 35911991.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14190289 + 5721664 = 3767^2 + 2392^2 .

It is an emirp because it is prime and its reverse (35911991) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 19911953 - 2¹⁸ = 19649809 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (19911959) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9955976 + 9955977.

It is an arithmetic number, because the mean of its divisors is an integer number (9955977).

Almost surely, 2^19911953 is an apocalyptic number.

It is an amenable number.

19911953 is a deficient number, since it is larger than the sum of its proper divisors (1).

19911953 is an equidigital number, since it uses as much as digits as its factorization.

19911953 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 10935, while the sum is 38.

The square root of 19911953 is about 4462.2811430926. The cubic root of 19911953 is about 271.0428484873.

Adding to 19911953 its sum of digits (38), we get a palindrome (19911991).

The spelling of 19911953 in words is "nineteen million, nine hundred eleven thousand, nine hundred fifty-three".