20121155 has 16 divisors (see below), whose sum is σ = 25218624. Its totient is φ = 15396480.

The previous prime is 20121137. The next prime is 20121169. The reversal of 20121155 is 55112102.

It is not a de Polignac number, because 20121155 - 2⁶ = 20121091 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10394 + ... + 12176.

It is an arithmetic number, because the mean of its divisors is an integer number (1576164).

Almost surely, 2^20121155 is an apocalyptic number.

20121155 is a deficient number, since it is larger than the sum of its proper divisors (5097469).

20121155 is a wasteful number, since it uses less digits than its factorization.

20121155 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1886.

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

The square root of 20121155 is about 4485.6610438151. The cubic root of 20121155 is about 271.9887673778.

Adding to 20121155 its reverse (55112102), we get a palindrome (75233257).

The spelling of 20121155 in words is "twenty million, one hundred twenty-one thousand, one hundred fifty-five".