78857221 has 8 divisors (see below), whose sum is σ = 80446464. Its totient is φ = 77283360.

The previous prime is 78857173. The next prime is 78857231. The reversal of 78857221 is 12275887.

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

It is a cyclic number.

It is not a de Polignac number, because 78857221 - 2⁹ = 78856709 is a prime.

It is a super-2 number, since 2×78857221² = 12436922607685682, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78857231) 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, 6801 + ... + 14281.

It is an arithmetic number, because the mean of its divisors is an integer number (10055808).

Almost surely, 2^78857221 is an apocalyptic number.

It is an amenable number.

78857221 is a deficient number, since it is larger than the sum of its proper divisors (1589243).

78857221 is a wasteful number, since it uses less digits than its factorization.

78857221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7691.

The product of its digits is 62720, while the sum is 40.

The square root of 78857221 is about 8880.1588386695. The cubic root of 78857221 is about 428.8253881211.

The spelling of 78857221 in words is "seventy-eight million, eight hundred fifty-seven thousand, two hundred twenty-one".