221681928 has 32 divisors (see below), whose sum is σ = 596836800. Its totient is φ = 68209728.

The previous prime is 221681917. The next prime is 221681963. The reversal of 221681928 is 829186122.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 354948 + ... + 355571.

It is an arithmetic number, because the mean of its divisors is an integer number (18651150).

Almost surely, 2^221681928 is an apocalyptic number.

It is an amenable number.

221681928 is an abundant number, since it is smaller than the sum of its proper divisors (375154872).

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

221681928 is a wasteful number, since it uses less digits than its factorization.

221681928 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 710541 (or 710537 counting only the distinct ones).

The product of its digits is 27648, while the sum is 39.

The square root of 221681928 is about 14888.9868023314. The cubic root of 221681928 is about 605.2155760230.

The spelling of 221681928 in words is "two hundred twenty-one million, six hundred eighty-one thousand, nine hundred twenty-eight".