221978464 has 12 divisors (see below), whose sum is σ = 437020164. Its totient is φ = 110989216.

The previous prime is 221978461. The next prime is 221978489. The reversal of 221978464 is 464879122.

It is a hoax number, since the sum of its digits (43) coincides with the sum of the digits of its distinct prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 221978464.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221978461) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3468382 + ... + 3468445.

It is an arithmetic number, because the mean of its divisors is an integer number (36418347).

Almost surely, 2^221978464 is an apocalyptic number.

It is an amenable number.

221978464 is a deficient number, since it is larger than the sum of its proper divisors (215041700).

221978464 is an equidigital number, since it uses as much as digits as its factorization.

221978464 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6936837 (or 6936829 counting only the distinct ones).

The product of its digits is 193536, while the sum is 43.

The square root of 221978464 is about 14898.9417073831. The cubic root of 221978464 is about 605.4853142080.

The spelling of 221978464 in words is "two hundred twenty-one million, nine hundred seventy-eight thousand, four hundred sixty-four".