20721671006516 has 12 divisors (see below), whose sum is σ = 36325771621188. Its totient is φ = 10342879114752.

The previous prime is 20721671006501. The next prime is 20721671006539. The reversal of 20721671006516 is 61560017612702.

It can be written as a sum of positive squares in 2 ways, for example, as 20537174985616 + 184496020900 = 4531796^2 + 429530^2 .

It is a congruent number.

It is an unprimeable number.

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, 4489094531 + ... + 4489099146.

It is an arithmetic number, because the mean of its divisors is an integer number (3027147635099).

Almost surely, 2^{20721671006516} is an apocalyptic number.

It is an amenable number.

20721671006516 is a deficient number, since it is larger than the sum of its proper divisors (15604100614672).

20721671006516 is a wasteful number, since it uses less digits than its factorization.

20721671006516 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8978194258 (or 8978194256 counting only the distinct ones).

The product of its (nonzero) digits is 211680, while the sum is 44.

The spelling of 20721671006516 in words is "twenty trillion, seven hundred twenty-one billion, six hundred seventy-one million, six thousand, five hundred sixteen".