20356505161 has 4 divisors (see below), whose sum is σ = 20386574532. Its totient is φ = 20326435792.

The previous prime is 20356505131. The next prime is 20356505201. The reversal of 20356505161 is 16150565302.

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 18750098761 + 1606406400 = 136931^2 + 40080^2 .

It is a cyclic number.

It is not a de Polignac number, because 20356505161 - 2⁷ = 20356505033 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20356505111) 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, 15033670 + ... + 15035023.

It is an arithmetic number, because the mean of its divisors is an integer number (5096643633).

Almost surely, 2^20356505161 is an apocalyptic number.

It is an amenable number.

20356505161 is a deficient number, since it is larger than the sum of its proper divisors (30069371).

20356505161 is an equidigital number, since it uses as much as digits as its factorization.

20356505161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30069370.

The product of its (nonzero) digits is 27000, while the sum is 34.

The spelling of 20356505161 in words is "twenty billion, three hundred fifty-six million, five hundred five thousand, one hundred sixty-one".