20721389894408 has 32 divisors (see below), whose sum is σ = 44488204853760. Its totient is φ = 8863550367360.

The previous prime is 20721389894357. The next prime is 20721389894411. The reversal of 20721389894408 is 80449898312702.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 355081016 + ... + 355139367.

It is an arithmetic number, because the mean of its divisors is an integer number (1390256401680).

Almost surely, 2^{20721389894408} is an apocalyptic number.

20721389894408 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

20721389894408 is an abundant number, since it is smaller than the sum of its proper divisors (23766814959352).

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

20721389894408 is a wasteful number, since it uses less digits than its factorization.

20721389894408 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 710220917 (or 710220913 counting only the distinct ones).

The product of its (nonzero) digits is 55738368, while the sum is 65.

The spelling of 20721389894408 in words is "twenty trillion, seven hundred twenty-one billion, three hundred eighty-nine million, eight hundred ninety-four thousand, four hundred eight".