21027129198809 has 16 divisors (see below), whose sum is σ = 21958304037120. Its totient is φ = 20116598080320.

The previous prime is 21027129198781. The next prime is 21027129198857. The reversal of 21027129198809 is 90889192172012.

It is a cyclic number.

It is not a de Polignac number, because 21027129198809 - 2²⁰ = 21027128150233 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21027129198899) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9749669 + ... + 11709410.

It is an arithmetic number, because the mean of its divisors is an integer number (1372394002320).

Almost surely, 2^{21027129198809} is an apocalyptic number.

It is an amenable number.

21027129198809 is a deficient number, since it is larger than the sum of its proper divisors (931174838311).

21027129198809 is a wasteful number, since it uses less digits than its factorization.

21027129198809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21459560.

The product of its (nonzero) digits is 2612736, while the sum is 59.

The spelling of 21027129198809 in words is "twenty-one trillion, twenty-seven billion, one hundred twenty-nine million, one hundred ninety-eight thousand, eight hundred nine".