21101121 has 8 divisors (see below), whose sum is σ = 31260960. Its totient is φ = 14067396.

The previous prime is 21101033. The next prime is 21101123. The reversal of 21101121 is 12110112.

It is a happy number.

It is not a de Polignac number, because 21101121 - 2⁷ = 21100993 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is not an unprimeable number, because it can be changed into a prime (21101123) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 390735 + ... + 390788.

It is an arithmetic number, because the mean of its divisors is an integer number (3907620).

Almost surely, 2^21101121 is an apocalyptic number.

It is an amenable number.

21101121 is a deficient number, since it is larger than the sum of its proper divisors (10159839).

21101121 is an equidigital number, since it uses as much as digits as its factorization.

21101121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 781532 (or 781526 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 9.

The square root of 21101121 is about 4593.5956504682. The cubic root of 21101121 is about 276.3345423492.

Adding to 21101121 its reverse (12110112), we get a palindrome (33211233).

The spelling of 21101121 in words is "twenty-one million, one hundred one thousand, one hundred twenty-one".