78635221 has 4 divisors (see below), whose sum is σ = 89868832. Its totient is φ = 67401612.

The previous prime is 78635209. The next prime is 78635309. The reversal of 78635221 is 12253687.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 78635221 - 2⁹ = 78634709 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78635201) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5616795 + ... + 5616808.

It is an arithmetic number, because the mean of its divisors is an integer number (22467208).

Almost surely, 2^78635221 is an apocalyptic number.

It is an amenable number.

78635221 is a deficient number, since it is larger than the sum of its proper divisors (11233611).

78635221 is a wasteful number, since it uses less digits than its factorization.

78635221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11233610.

The product of its digits is 20160, while the sum is 34.

The square root of 78635221 is about 8867.6502524626. The cubic root of 78635221 is about 428.4225980728.

The spelling of 78635221 in words is "seventy-eight million, six hundred thirty-five thousand, two hundred twenty-one".