20647767421 has 8 divisors (see below), whose sum is σ = 20718037080. Its totient is φ = 20577530688.

The previous prime is 20647767389. The next prime is 20647767433. The reversal of 20647767421 is 12476774602.

It can be written as a sum of positive squares in 4 ways, for example, as 636552900 + 20011214521 = 25230^2 + 141461^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20647767421 - 2⁵ = 20647767389 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 (20648767421) 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 7 ways as a sum of consecutive naturals, for example, 2492875 + ... + 2501143.

It is an arithmetic number, because the mean of its divisors is an integer number (2589754635).

Almost surely, 2^20647767421 is an apocalyptic number.

It is an amenable number.

20647767421 is a deficient number, since it is larger than the sum of its proper divisors (70269659).

20647767421 is an equidigital number, since it uses as much as digits as its factorization.

20647767421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16463.

The product of its (nonzero) digits is 790272, while the sum is 46.

The spelling of 20647767421 in words is "twenty billion, six hundred forty-seven million, seven hundred sixty-seven thousand, four hundred twenty-one".