78721434 has 48 divisors (see below), whose sum is σ = 187372224. Its totient is φ = 23688000.

The previous prime is 78721421. The next prime is 78721439. The reversal of 78721434 is 43412787.

It is a happy number.

It is an alternating number because its digits alternate between odd and even.

It is not an unprimeable number, because it can be changed into a prime (78721439) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 28582 + ... + 31214.

It is an arithmetic number, because the mean of its divisors is an integer number (3903588).

Almost surely, 2^78721434 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 78721434, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (93686112).

78721434 is an abundant number, since it is smaller than the sum of its proper divisors (108650790).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

78721434 is a wasteful number, since it uses less digits than its factorization.

78721434 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2803 (or 2800 counting only the distinct ones).

The product of its digits is 37632, while the sum is 36.

The square root of 78721434 is about 8872.5100169005. The cubic root of 78721434 is about 428.5791102433.

The spelling of 78721434 in words is "seventy-eight million, seven hundred twenty-one thousand, four hundred thirty-four".