20904536172649 has 4 divisors (see below), whose sum is σ = 20905267205764. Its totient is φ = 20903805139536.

The previous prime is 20904536172643. The next prime is 20904536172739. The reversal of 20904536172649 is 94627163540902.

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 17680511232400 + 3224024940249 = 4204820^2 + 1795557^2 .

It is a cyclic number.

It is not a de Polignac number, because 20904536172649 - 2³⁵ = 20870176434281 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20904536172593 and 20904536172602.

It is not an unprimeable number, because it can be changed into a prime (20904536172643) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 365473662 + ... + 365530855.

It is an arithmetic number, because the mean of its divisors is an integer number (5226316801441).

Almost surely, 2^{20904536172649} is an apocalyptic number.

It is an amenable number.

20904536172649 is a deficient number, since it is larger than the sum of its proper divisors (731033115).

20904536172649 is an equidigital number, since it uses as much as digits as its factorization.

20904536172649 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 731033114.

The product of its (nonzero) digits is 19595520, while the sum is 58.

The spelling of 20904536172649 in words is "twenty trillion, nine hundred four billion, five hundred thirty-six million, one hundred seventy-two thousand, six hundred forty-nine".