21171756680016 has 20 divisors (see below), whose sum is σ = 54693704756832. Its totient is φ = 7057252226656.

The previous prime is 21171756679987. The next prime is 21171756680093. The reversal of 21171756680016 is 61008665717112.

It is a super-2 number, since 2×21171756680016² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 220539132036 + ... + 220539132131.

Almost surely, 2^{21171756680016} is an apocalyptic number.

It is an amenable number.

21171756680016 is an abundant number, since it is smaller than the sum of its proper divisors (33521948076816).

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

21171756680016 is a wasteful number, since it uses less digits than its factorization.

21171756680016 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 441078264178 (or 441078264172 counting only the distinct ones).

The product of its (nonzero) digits is 846720, while the sum is 51.

The spelling of 21171756680016 in words is "twenty-one trillion, one hundred seventy-one billion, seven hundred fifty-six million, six hundred eighty thousand, sixteen".