78431551 has 4 divisors (see below), whose sum is σ = 85561704. Its totient is φ = 71301400.

The previous prime is 78431539. The next prime is 78431567. The reversal of 78431551 is 15513487.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 78431551 - 2⁹ = 78431039 is a prime.

It is a pancake number, because a pancake can be divided into 78431551 parts by 12524 straight cuts.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78431501) 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, 3565060 + ... + 3565081.

It is an arithmetic number, because the mean of its divisors is an integer number (21390426).

Almost surely, 2^78431551 is an apocalyptic number.

78431551 is a deficient number, since it is larger than the sum of its proper divisors (7130153).

78431551 is a wasteful number, since it uses less digits than its factorization.

78431551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7130152.

The product of its digits is 16800, while the sum is 34.

The square root of 78431551 is about 8856.1589303716. The cubic root of 78431551 is about 428.0523980889.

The spelling of 78431551 in words is "seventy-eight million, four hundred thirty-one thousand, five hundred fifty-one".