20635336621 has 4 divisors (see below), whose sum is σ = 20666555644. Its totient is φ = 20604117600.

The previous prime is 20635336597. The next prime is 20635336639. The reversal of 20635336621 is 12663353602.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12663353602 = 2 ⋅6331676801.

It can be written as a sum of positive squares in 2 ways, for example, as 7865206596 + 12770130025 = 88686^2 + 113005^2 .

It is a cyclic number.

It is not a de Polignac number, because 20635336621 - 2⁷ = 20635336493 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 (20635336691) 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, 15608520 + ... + 15609841.

It is an arithmetic number, because the mean of its divisors is an integer number (5166638911).

Almost surely, 2^20635336621 is an apocalyptic number.

It is an amenable number.

20635336621 is a deficient number, since it is larger than the sum of its proper divisors (31219023).

20635336621 is an equidigital number, since it uses as much as digits as its factorization.

20635336621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31219022.

The product of its (nonzero) digits is 116640, while the sum is 37.

The spelling of 20635336621 in words is "twenty billion, six hundred thirty-five million, three hundred thirty-six thousand, six hundred twenty-one".