78321909 has 8 divisors (see below), whose sum is σ = 104971072. Its totient is φ = 51943680.

The previous prime is 78321889. The next prime is 78321911. The reversal of 78321909 is 90912387.

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

It is not a de Polignac number, because 78321909 - 2⁸ = 78321653 is a prime.

It is a super-2 number, since 2×78321909² = 12268642858808562, 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 (78321109) 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, 67057 + ... + 68214.

It is an arithmetic number, because the mean of its divisors is an integer number (13121384).

Almost surely, 2^78321909 is an apocalyptic number.

It is an amenable number.

78321909 is a deficient number, since it is larger than the sum of its proper divisors (26649163).

78321909 is a wasteful number, since it uses less digits than its factorization.

78321909 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 135467.

The product of its (nonzero) digits is 27216, while the sum is 39.

The square root of 78321909 is about 8849.9666101065. The cubic root of 78321909 is about 427.8528423110.

The spelling of 78321909 in words is "seventy-eight million, three hundred twenty-one thousand, nine hundred nine".