19879421 has 2 divisors, whose sum is σ = 19879422. Its totient is φ = 19879420.

The previous prime is 19879417. The next prime is 19879427. The reversal of 19879421 is 12497891.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19456921 + 422500 = 4411^2 + 650^2 .

It is a cyclic number.

It is not a de Polignac number, because 19879421 - 2² = 19879417 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19879427) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9939710 + 9939711.

It is an arithmetic number, because the mean of its divisors is an integer number (9939711).

Almost surely, 2^19879421 is an apocalyptic number.

It is an amenable number.

19879421 is a deficient number, since it is larger than the sum of its proper divisors (1).

19879421 is an equidigital number, since it uses as much as digits as its factorization.

19879421 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 36288, while the sum is 41.

The square root of 19879421 is about 4458.6344322001. The cubic root of 19879421 is about 270.8951587665.

The spelling of 19879421 in words is "nineteen million, eight hundred seventy-nine thousand, four hundred twenty-one".