20909121 has 16 divisors (see below), whose sum is σ = 28403328. Its totient is φ = 13680000.

The previous prime is 20909117. The next prime is 20909173. The reversal of 20909121 is 12190902.

It is not a de Polignac number, because 20909121 - 2² = 20909117 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20909091 and 20909100.

It is not an unprimeable number, because it can be changed into a prime (20909321) 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 15 ways as a sum of consecutive naturals, for example, 45525 + ... + 45981.

It is an arithmetic number, because the mean of its divisors is an integer number (1775208).

Almost surely, 2^20909121 is an apocalyptic number.

It is an amenable number.

20909121 is a deficient number, since it is larger than the sum of its proper divisors (7494207).

20909121 is a wasteful number, since it uses less digits than its factorization.

20909121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 712.

The product of its (nonzero) digits is 324, while the sum is 24.

The square root of 20909121 is about 4572.6492321192. The cubic root of 20909121 is about 275.4938607749.

It can be divided in two parts, 2090 and 9121, that added together give a palindrome (11211).

The spelling of 20909121 in words is "twenty million, nine hundred nine thousand, one hundred twenty-one".