20155204121 has 4 divisors (see below), whose sum is σ = 21705604452. Its totient is φ = 18604803792.

The previous prime is 20155204067. The next prime is 20155204127. The reversal of 20155204121 is 12140255102.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 7755268096 + 12399936025 = 88064^2 + 111355^2 .

It is a cyclic number.

It is not a de Polignac number, because 20155204121 - 2¹⁴ = 20155187737 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20155204127) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 775200146 + ... + 775200171.

It is an arithmetic number, because the mean of its divisors is an integer number (5426401113).

Almost surely, 2^20155204121 is an apocalyptic number.

It is an amenable number.

20155204121 is a deficient number, since it is larger than the sum of its proper divisors (1550400331).

20155204121 is a wasteful number, since it uses less digits than its factorization.

20155204121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1550400330.

The product of its (nonzero) digits is 800, while the sum is 23.

Adding to 20155204121 its reverse (12140255102), we get a palindrome (32295459223).

The spelling of 20155204121 in words is "twenty billion, one hundred fifty-five million, two hundred four thousand, one hundred twenty-one".