78991407 has 48 divisors (see below), whose sum is σ = 131459328. Its totient is φ = 45239040.

The previous prime is 78991399. The next prime is 78991439. The reversal of 78991407 is 70419987.

It is not a de Polignac number, because 78991407 - 2³ = 78991399 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78991807) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 257148 + ... + 257454.

It is an arithmetic number, because the mean of its divisors is an integer number (2738736).

Almost surely, 2^78991407 is an apocalyptic number.

78991407 is a deficient number, since it is larger than the sum of its proper divisors (52467921).

78991407 is a wasteful number, since it uses less digits than its factorization.

78991407 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 460 (or 457 counting only the distinct ones).

The product of its (nonzero) digits is 127008, while the sum is 45.

The square root of 78991407 is about 8887.7110101533. The cubic root of 78991407 is about 429.0684846736.

The spelling of 78991407 in words is "seventy-eight million, nine hundred ninety-one thousand, four hundred seven".