21107121 has 8 divisors (see below), whose sum is σ = 32163264. Its totient is φ = 12061200.

The previous prime is 21107117. The next prime is 21107167. The reversal of 21107121 is 12170112.

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

It is not a de Polignac number, because 21107121 - 2² = 21107117 is a prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21107121.

It is not an unprimeable number, because it can be changed into a prime (21107101) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 502530 + ... + 502571.

It is an arithmetic number, because the mean of its divisors is an integer number (4020408).

Almost surely, 2^21107121 is an apocalyptic number.

21107121 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21107121 is a deficient number, since it is larger than the sum of its proper divisors (11056143).

21107121 is a wasteful number, since it uses less digits than its factorization.

21107121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1005111.

The product of its (nonzero) digits is 28, while the sum is 15.

The square root of 21107121 is about 4594.2486872175. The cubic root of 21107121 is about 276.3607313232.

Adding to 21107121 its reverse (12170112), we get a palindrome (33277233).

The spelling of 21107121 in words is "twenty-one million, one hundred seven thousand, one hundred twenty-one".