20678342721653 has 4 divisors (see below), whose sum is σ = 20682920619180. Its totient is φ = 20673764824128.

The previous prime is 20678342721649. The next prime is 20678342721677. The reversal of 20678342721653 is 35612724387602.

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 1308283015204 + 19370059706449 = 1143802^2 + 4401143^2 .

It is a cyclic number.

It is not a de Polignac number, because 20678342721653 - 2² = 20678342721649 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20678342721613) 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, 2288941988 + ... + 2288951021.

It is an arithmetic number, because the mean of its divisors is an integer number (5170730154795).

Almost surely, 2^{20678342721653} is an apocalyptic number.

It is an amenable number.

20678342721653 is a deficient number, since it is larger than the sum of its proper divisors (4577897527).

20678342721653 is an equidigital number, since it uses as much as digits as its factorization.

20678342721653 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4577897526.

The product of its (nonzero) digits is 20321280, while the sum is 56.

The spelling of 20678342721653 in words is "twenty trillion, six hundred seventy-eight billion, three hundred forty-two million, seven hundred twenty-one thousand, six hundred fifty-three".