21020210019989 has 4 divisors (see below), whose sum is σ = 21059064382860. Its totient is φ = 20981355657120.

The previous prime is 21020210019971. The next prime is 21020210020057. The reversal of 21020210019989 is 98991001202012.

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

It can be written as a sum of positive squares in 2 ways, for example, as 2463198413764 + 18557011606225 = 1569458^2 + 4307785^2 .

It is a cyclic number.

It is not a de Polignac number, because 21020210019989 - 2²⁴ = 21020193242773 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 (21020210019689) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 19427180624 + ... + 19427181705.

It is an arithmetic number, because the mean of its divisors is an integer number (5264766095715).

Almost surely, 2^{21020210019989} is an apocalyptic number.

It is an amenable number.

21020210019989 is a deficient number, since it is larger than the sum of its proper divisors (38854362871).

21020210019989 is an equidigital number, since it uses as much as digits as its factorization.

21020210019989 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38854362870.

The product of its (nonzero) digits is 46656, while the sum is 44.

The spelling of 21020210019989 in words is "twenty-one trillion, twenty billion, two hundred ten million, nineteen thousand, nine hundred eighty-nine".