19912001 has 2 divisors, whose sum is σ = 19912002. Its totient is φ = 19912000.

The previous prime is 19911979. The next prime is 19912007. The reversal of 19912001 is 10021991.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11937025 + 7974976 = 3455^2 + 2824^2 .

It is a cyclic number.

It is not a de Polignac number, because 19912001 - 2¹⁰ = 19910977 is a prime.

It is a Chen prime.

It is equal to p_1265333 and since 19912001 and 1265333 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (19912007) by changing a digit.

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

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9956000 + 9956001.

It is an arithmetic number, because the mean of its divisors is an integer number (9956001).

Almost surely, 2^19912001 is an apocalyptic number.

It is an amenable number.

19912001 is a deficient number, since it is larger than the sum of its proper divisors (1).

19912001 is an equidigital number, since it uses as much as digits as its factorization.

19912001 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 162, while the sum is 23.

The square root of 19912001 is about 4462.2865215044. The cubic root of 19912001 is about 271.0430662802.

Adding to 19912001 its reverse (10021991), we get a palindrome (29933992).

The spelling of 19912001 in words is "nineteen million, nine hundred twelve thousand, one".