20668209408 has 972 divisors, whose sum is σ = 81584144460. Its totient is φ = 4995809280.

The previous prime is 20668209307. The next prime is 20668209467. The reversal of 20668209408 is 80490286602.

It can be written as a sum of positive squares in 2 ways, for example, as 9958443264 + 10709766144 = 99792^2 + 103488^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 107 ways as a sum of consecutive naturals, for example, 232227028 + ... + 232227116.

It is an arithmetic number, because the mean of its divisors is an integer number (83934305).

Almost surely, 2^20668209408 is an apocalyptic number.

20668209408 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20668209408, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40792072230).

20668209408 is an abundant number, since it is smaller than the sum of its proper divisors (60915935052).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20668209408 is a wasteful number, since it uses less digits than its factorization.

20668209408 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 164 (or 129 counting only the distinct ones).

The product of its (nonzero) digits is 331776, while the sum is 45.

The spelling of 20668209408 in words is "twenty billion, six hundred sixty-eight million, two hundred nine thousand, four hundred eight".