21001020021109 has 16 divisors (see below), whose sum is σ = 21076219232640. Its totient is φ = 20925995683840.

The previous prime is 21001020021103. The next prime is 21001020021167. The reversal of 21001020021109 is 90112002010012.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21001020021109 - 2²³ = 21001011632501 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 (21001020021103) 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, 671823522 + ... + 671854780.

It is an arithmetic number, because the mean of its divisors is an integer number (1317263702040).

Almost surely, 2^{21001020021109} is an apocalyptic number.

It is an amenable number.

21001020021109 is a deficient number, since it is larger than the sum of its proper divisors (75199211531).

21001020021109 is a wasteful number, since it uses less digits than its factorization.

21001020021109 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33980.

The product of its (nonzero) digits is 72, while the sum is 19.

The spelling of 21001020021109 in words is "twenty-one trillion, one billion, twenty million, twenty-one thousand, one hundred nine".