21106550181 has 4 divisors (see below), whose sum is σ = 28142066912. Its totient is φ = 14071033452.

The previous prime is 21106550177. The next prime is 21106550203. The reversal of 21106550181 is 18105560112.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 21106550181 - 2² = 21106550177 is a prime.

It is a super-2 number, since 2×21106550181² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21106550131) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3517758361 + ... + 3517758366.

It is an arithmetic number, because the mean of its divisors is an integer number (7035516728).

Almost surely, 2^21106550181 is an apocalyptic number.

It is an amenable number.

21106550181 is a deficient number, since it is larger than the sum of its proper divisors (7035516731).

21106550181 is an equidigital number, since it uses as much as digits as its factorization.

21106550181 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7035516730.

The product of its (nonzero) digits is 2400, while the sum is 30.

The spelling of 21106550181 in words is "twenty-one billion, one hundred six million, five hundred fifty thousand, one hundred eighty-one".