78720389 has 8 divisors (see below), whose sum is σ = 86533920. Its totient is φ = 71016400.

The previous prime is 78720373. The next prime is 78720403. The reversal of 78720389 is 98302787.

It is a happy number.

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 78720389 - 2⁴ = 78720373 is a prime.

It is a super-2 number, since 2×78720389² = 12393799288622642, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78720359) 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, 25874 + ... + 28755.

It is an arithmetic number, because the mean of its divisors is an integer number (10816740).

Almost surely, 2^78720389 is an apocalyptic number.

It is an amenable number.

78720389 is a deficient number, since it is larger than the sum of its proper divisors (7813531).

78720389 is a wasteful number, since it uses less digits than its factorization.

78720389 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54771.

The product of its (nonzero) digits is 169344, while the sum is 44.

The square root of 78720389 is about 8872.4511269434. The cubic root of 78720389 is about 428.5772138214.

The spelling of 78720389 in words is "seventy-eight million, seven hundred twenty thousand, three hundred eighty-nine".