221287668 has 24 divisors (see below), whose sum is σ = 590100672. Its totient is φ = 63225024.

The previous prime is 221287643. The next prime is 221287679. The reversal of 221287668 is 866782122.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1317105 + ... + 1317272.

It is an arithmetic number, because the mean of its divisors is an integer number (24587528).

Almost surely, 2^221287668 is an apocalyptic number.

221287668 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

221287668 is an abundant number, since it is smaller than the sum of its proper divisors (368813004).

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

221287668 is a wasteful number, since it uses less digits than its factorization.

221287668 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2634391 (or 2634389 counting only the distinct ones).

The product of its digits is 129024, while the sum is 42.

The square root of 221287668 is about 14875.7409227238. The cubic root of 221287668 is about 604.8565723340.

The spelling of 221287668 in words is "two hundred twenty-one million, two hundred eighty-seven thousand, six hundred sixty-eight".