221978564478 has 32 divisors (see below), whose sum is σ = 538129854720. Its totient is φ = 67266231480.

The previous prime is 221978564449. The next prime is 221978564491. The reversal of 221978564478 is 874465879122.

It is a happy number.

221978564478 is a `hidden beast` number, since 2 + 21 + 9 + 7 + 8 + 564 + 47 + 8 = 666.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 186850050 + ... + 186851237.

It is an arithmetic number, because the mean of its divisors is an integer number (16816557960).

Almost surely, 2^221978564478 is an apocalyptic number.

221978564478 is an abundant number, since it is smaller than the sum of its proper divisors (316151290242).

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

221978564478 is a wasteful number, since it uses less digits than its factorization.

221978564478 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 373701309 (or 373701303 counting only the distinct ones).

The product of its digits is 54190080, while the sum is 63.

The spelling of 221978564478 in words is "two hundred twenty-one billion, nine hundred seventy-eight million, five hundred sixty-four thousand, four hundred seventy-eight".