21978036216 has 48 divisors (see below), whose sum is σ = 62111846160. Its totient is φ = 7007489280.

The previous prime is 21978036209. The next prime is 21978036217. The reversal of 21978036216 is 61263087912.

21978036216 is a `hidden beast` number, since 2 + 19 + 7 + 8 + 0 + 3 + 621 + 6 = 666.

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21978036217) by changing a digit.

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 11 ways as a sum of consecutive naturals, for example, 6634225 + ... + 6637536.

It is an arithmetic number, because the mean of its divisors is an integer number (1293996795).

Almost surely, 2^21978036216 is an apocalyptic number.

It is an amenable number.

21978036216 is an abundant number, since it is smaller than the sum of its proper divisors (40133809944).

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

21978036216 is a wasteful number, since it uses less digits than its factorization.

21978036216 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13271796 (or 13271789 counting only the distinct ones).

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

The spelling of 21978036216 in words is "twenty-one billion, nine hundred seventy-eight million, thirty-six thousand, two hundred sixteen".