20155121 has 12 divisors (see below), whose sum is σ = 24081588. Its totient is φ = 16807392.

The previous prime is 20155117. The next prime is 20155127. The reversal of 20155121 is 12155102.

It can be written as a sum of positive squares in 2 ways, for example, as 10144225 + 10010896 = 3185^2 + 3164^2 .

It is not a de Polignac number, because 20155121 - 2² = 20155117 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20155121.

It is not an unprimeable number, because it can be changed into a prime (20155127) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3746 + ... + 7371.

It is an arithmetic number, because the mean of its divisors is an integer number (2006799).

Almost surely, 2^20155121 is an apocalyptic number.

It is an amenable number.

20155121 is a deficient number, since it is larger than the sum of its proper divisors (3926467).

20155121 is a wasteful number, since it uses less digits than its factorization.

20155121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11168 (or 11161 counting only the distinct ones).

The product of its (nonzero) digits is 100, while the sum is 17.

The square root of 20155121 is about 4489.4455114190. The cubic root of 20155121 is about 272.1417270694.

The spelling of 20155121 in words is "twenty million, one hundred fifty-five thousand, one hundred twenty-one".