20561718216 has 64 divisors (see below), whose sum is σ = 55386172800. Its totient is φ = 6323516928.

The previous prime is 20561718143. The next prime is 20561718257. The reversal of 20561718216 is 61281716502.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 651325 + ... + 682163.

It is an arithmetic number, because the mean of its divisors is an integer number (865408950).

Almost surely, 2^20561718216 is an apocalyptic number.

20561718216 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

20561718216 is an abundant number, since it is smaller than the sum of its proper divisors (34824454584).

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

20561718216 is a wasteful number, since it uses less digits than its factorization.

20561718216 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32998 (or 32994 counting only the distinct ones).

The product of its (nonzero) digits is 40320, while the sum is 39.

The spelling of 20561718216 in words is "twenty billion, five hundred sixty-one million, seven hundred eighteen thousand, two hundred sixteen".