78729397 has 4 divisors (see below), whose sum is σ = 83360556. Its totient is φ = 74098240.

The previous prime is 78729373. The next prime is 78729419. The reversal of 78729397 is 79392787.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 45077796 + 33651601 = 6714^2 + 5801^2 .

It is not a de Polignac number, because 78729397 - 2⁷ = 78729269 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 (78729317) 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, 2315554 + ... + 2315587.

It is an arithmetic number, because the mean of its divisors is an integer number (20840139).

Almost surely, 2^78729397 is an apocalyptic number.

It is an amenable number.

78729397 is a deficient number, since it is larger than the sum of its proper divisors (4631159).

78729397 is a wasteful number, since it uses less digits than its factorization.

78729397 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4631158.

The product of its digits is 1333584, while the sum is 52.

The square root of 78729397 is about 8872.9587511720. The cubic root of 78729397 is about 428.5935606084.

The spelling of 78729397 in words is "seventy-eight million, seven hundred twenty-nine thousand, three hundred ninety-seven".