20665084798621 has 2 divisors, whose sum is σ = 20665084798622. Its totient is φ = 20665084798620.

The previous prime is 20665084798577. The next prime is 20665084798637. The reversal of 20665084798621 is 12689748056602.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19853128819225 + 811955979396 = 4455685^2 + 901086^2 .

It is a cyclic number.

It is not a de Polignac number, because 20665084798621 - 2²¹ = 20665082701469 is a prime.

It is a super-2 number, since 2×20665084798621² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20665084708621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10332542399310 + 10332542399311.

It is an arithmetic number, because the mean of its divisors is an integer number (10332542399311).

Almost surely, 2^{20665084798621} is an apocalyptic number.

It is an amenable number.

20665084798621 is a deficient number, since it is larger than the sum of its proper divisors (1).

20665084798621 is an equidigital number, since it uses as much as digits as its factorization.

20665084798621 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 69672960, while the sum is 64.

The spelling of 20665084798621 in words is "twenty trillion, six hundred sixty-five billion, eighty-four million, seven hundred ninety-eight thousand, six hundred twenty-one".