21019845679 has 4 divisors (see below), whose sum is σ = 24022680784. Its totient is φ = 18017010576.

The previous prime is 21019845661. The next prime is 21019845727. The reversal of 21019845679 is 97654891012.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21019845679 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21019845079) 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 in 3 ways as a sum of consecutive naturals, for example, 1501417542 + ... + 1501417555.

It is an arithmetic number, because the mean of its divisors is an integer number (6005670196).

Almost surely, 2^21019845679 is an apocalyptic number.

21019845679 is a deficient number, since it is larger than the sum of its proper divisors (3002835105).

21019845679 is an equidigital number, since it uses as much as digits as its factorization.

21019845679 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3002835104.

The product of its (nonzero) digits is 1088640, while the sum is 52.

The spelling of 21019845679 in words is "twenty-one billion, nineteen million, eight hundred forty-five thousand, six hundred seventy-nine".