21978660312 has 192 divisors, whose sum is σ = 72361317600. Its totient is φ = 6160976640.

The previous prime is 21978660293. The next prime is 21978660349. The reversal of 21978660312 is 21306687912.

21978660312 is a `hidden beast` number, since 21 + 9 + 7 + 8 + 6 + 603 + 12 = 666.

It is a super-2 number, since 2×21978660312² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 541362 + ... + 580542.

Almost surely, 2^21978660312 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21978660312, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36180658800).

21978660312 is an abundant number, since it is smaller than the sum of its proper divisors (50382657288).

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

21978660312 is a wasteful number, since it uses less digits than its factorization.

21978660312 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39263 (or 39246 counting only the distinct ones).

The product of its (nonzero) digits is 217728, while the sum is 45.

The spelling of 21978660312 in words is "twenty-one billion, nine hundred seventy-eight million, six hundred sixty thousand, three hundred twelve".