21010020019 has 4 divisors (see below), whose sum is σ = 21055398496. Its totient is φ = 20964641544.

The previous prime is 21010020007. The next prime is 21010020047. The reversal of 21010020019 is 91002001012.

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-21010020019 is a prime.

It is a super-2 number, since 2×21010020019² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21010019984 and 21010020011.

It is not an unprimeable number, because it can be changed into a prime (21010020919) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 22688544 + ... + 22689469.

It is an arithmetic number, because the mean of its divisors is an integer number (5263849624).

Almost surely, 2^21010020019 is an apocalyptic number.

21010020019 is a deficient number, since it is larger than the sum of its proper divisors (45378477).

21010020019 is an equidigital number, since it uses as much as digits as its factorization.

21010020019 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 45378476.

The product of its (nonzero) digits is 36, while the sum is 16.

The spelling of 21010020019 in words is "twenty-one billion, ten million, twenty thousand, nineteen".