21721051085373 has 48 divisors (see below), whose sum is σ = 33521669101440. Its totient is φ = 13523624497152.

The previous prime is 21721051085287. The next prime is 21721051085387. The reversal of 21721051085373 is 37358015012712.

21721051085373 is a `hidden beast` number, since 2 + 1 + 7 + 2 + 1 + 0 + 5 + 108 + 537 + 3 = 666.

It is not a de Polignac number, because 21721051085373 - 2¹⁸ = 21721050823229 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21721051085873) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 5362708 + ... + 8497101.

It is an arithmetic number, because the mean of its divisors is an integer number (698368106280).

Almost surely, 2^{21721051085373} is an apocalyptic number.

21721051085373 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

It is an amenable number.

21721051085373 is a deficient number, since it is larger than the sum of its proper divisors (11800618016067).

21721051085373 is a wasteful number, since it uses less digits than its factorization.

21721051085373 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13860018 (or 13860015 counting only the distinct ones).

The product of its (nonzero) digits is 352800, while the sum is 45.

The spelling of 21721051085373 in words is "twenty-one trillion, seven hundred twenty-one billion, fifty-one million, eighty-five thousand, three hundred seventy-three".