221978307 has 8 divisors (see below), whose sum is σ = 296058880. Its totient is φ = 147941640.

The previous prime is 221978291. The next prime is 221978357. The reversal of 221978307 is 703879122.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 221978307 - 2⁴ = 221978291 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (221978357) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3582 + ... + 21372.

It is an arithmetic number, because the mean of its divisors is an integer number (37007360).

Almost surely, 2^221978307 is an apocalyptic number.

221978307 is a deficient number, since it is larger than the sum of its proper divisors (74080573).

221978307 is a wasteful number, since it uses less digits than its factorization.

221978307 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21953.

The product of its (nonzero) digits is 42336, while the sum is 39.

The square root of 221978307 is about 14898.9364385516. The cubic root of 221978307 is about 605.4851714596.

The spelling of 221978307 in words is "two hundred twenty-one million, nine hundred seventy-eight thousand, three hundred seven".