21001020021091 has 8 divisors (see below), whose sum is σ = 22910251902768. Its totient is φ = 19091796180000.

The previous prime is 21001020021029. The next prime is 21001020021103. The reversal of 21001020021091 is 19012002010012.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21001020021091 - 2¹¹ = 21001020019043 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21001020022091) 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 7 ways as a sum of consecutive naturals, for example, 4316941 + ... + 7787041.

It is an arithmetic number, because the mean of its divisors is an integer number (2863781487846).

Almost surely, 2^{21001020021091} is an apocalyptic number.

21001020021091 is a deficient number, since it is larger than the sum of its proper divisors (1909231881677).

21001020021091 is a wasteful number, since it uses less digits than its factorization.

21001020021091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4020293.

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

The spelling of 21001020021091 in words is "twenty-one trillion, one billion, twenty million, twenty-one thousand, ninety-one".