21002121100191 has 16 divisors (see below), whose sum is σ = 34912616894208. Its totient is φ = 10910192779200.

The previous prime is 21002121100187. The next prime is 21002121100229. The reversal of 21002121100191 is 19100112120012.

It is not a de Polignac number, because 21002121100191 - 2² = 21002121100187 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21002121100091) 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, 45459136350 + ... + 45459136811.

It is an arithmetic number, because the mean of its divisors is an integer number (2182038555888).

Almost surely, 2^{21002121100191} is an apocalyptic number.

21002121100191 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21002121100191 is a deficient number, since it is larger than the sum of its proper divisors (13910495794017).

21002121100191 is a wasteful number, since it uses less digits than its factorization.

21002121100191 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 90918273182.

The product of its (nonzero) digits is 72, while the sum is 21.

The spelling of 21002121100191 in words is "twenty-one trillion, two billion, one hundred twenty-one million, one hundred thousand, one hundred ninety-one".