78723551 has 4 divisors (see below), whose sum is σ = 79535232. Its totient is φ = 77911872.

The previous prime is 78723521. The next prime is 78723553. The reversal of 78723551 is 15532787.

It is a happy number.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-78723551 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 (78723553) 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, 405695 + ... + 405888.

It is an arithmetic number, because the mean of its divisors is an integer number (19883808).

Almost surely, 2^78723551 is an apocalyptic number.

78723551 is a deficient number, since it is larger than the sum of its proper divisors (811681).

78723551 is an equidigital number, since it uses as much as digits as its factorization.

78723551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 811680.

The product of its digits is 58800, while the sum is 38.

The square root of 78723551 is about 8872.6293171754. The cubic root of 78723551 is about 428.5829520341.

The spelling of 78723551 in words is "seventy-eight million, seven hundred twenty-three thousand, five hundred fifty-one".