19713121 has 2 divisors, whose sum is σ = 19713122. Its totient is φ = 19713120.

The previous prime is 19713101. The next prime is 19713131. The reversal of 19713121 is 12131791.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19580625 + 132496 = 4425^2 + 364^2 .

It is a cyclic number.

It is not a de Polignac number, because 19713121 - 2¹¹ = 19711073 is a prime.

It is not a weakly prime, because it can be changed into another prime (19713101) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9856560 + 9856561.

It is an arithmetic number, because the mean of its divisors is an integer number (9856561).

Almost surely, 2^19713121 is an apocalyptic number.

It is an amenable number.

19713121 is a deficient number, since it is larger than the sum of its proper divisors (1).

19713121 is an equidigital number, since it uses as much as digits as its factorization.

19713121 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 378, while the sum is 25.

The square root of 19713121 is about 4439.9460582309. The cubic root of 19713121 is about 270.1376572852.

The spelling of 19713121 in words is "nineteen million, seven hundred thirteen thousand, one hundred twenty-one".