20304155521 has 4 divisors (see below), whose sum is σ = 21866013652. Its totient is φ = 18742297392.

The previous prime is 20304155519. The next prime is 20304155539. The reversal of 20304155521 is 12555140302.

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 3107505025 + 17196650496 = 55745^2 + 131136^2 .

It is not a de Polignac number, because 20304155521 - 2¹ = 20304155519 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 20304155521.

It is not an unprimeable number, because it can be changed into a prime (20304155021) 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, 780929046 + ... + 780929071.

It is an arithmetic number, because the mean of its divisors is an integer number (5466503413).

Almost surely, 2^20304155521 is an apocalyptic number.

It is an amenable number.

20304155521 is a deficient number, since it is larger than the sum of its proper divisors (1561858131).

20304155521 is a wasteful number, since it uses less digits than its factorization.

20304155521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1561858130.

The product of its (nonzero) digits is 6000, while the sum is 28.

Adding to 20304155521 its reverse (12555140302), we get a palindrome (32859295823).

The spelling of 20304155521 in words is "twenty billion, three hundred four million, one hundred fifty-five thousand, five hundred twenty-one".