21780685008 has 60 divisors (see below), whose sum is σ = 60982145380. Its totient is φ = 7257074688.

The previous prime is 21780684977. The next prime is 21780685009. The reversal of 21780685008 is 80058608712.

21780685008 is a `hidden beast` number, since 2 + 1 + 7 + 80 + 68 + 500 + 8 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 12119367744 + 9661317264 = 110088^2 + 98292^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21780685009) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 312360 + ... + 375672.

Almost surely, 2^21780685008 is an apocalyptic number.

It is an amenable number.

21780685008 is an abundant number, since it is smaller than the sum of its proper divisors (39201460372).

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

21780685008 is a wasteful number, since it uses less digits than its factorization.

21780685008 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 65716 (or 65707 counting only the distinct ones).

The product of its (nonzero) digits is 215040, while the sum is 45.

The spelling of 21780685008 in words is "twenty-one billion, seven hundred eighty million, six hundred eighty-five thousand, eight".