78724442 has 4 divisors (see below), whose sum is σ = 118086666. Its totient is φ = 39362220.

The previous prime is 78724417. The next prime is 78724453. The reversal of 78724442 is 24442787.

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

It can be written as a sum of positive squares in only one way, i.e., 77986561 + 737881 = 8831^2 + 859^2 .

It is a super-2 number, since 2×78724442² = 12395075536422728, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 78724396 and 78724405.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 19681109 + ... + 19681112.

Almost surely, 2^78724442 is an apocalyptic number.

78724442 is a deficient number, since it is larger than the sum of its proper divisors (39362224).

78724442 is a wasteful number, since it uses less digits than its factorization.

78724442 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39362223.

The product of its digits is 100352, while the sum is 38.

The square root of 78724442 is about 8872.6795276286. The cubic root of 78724442 is about 428.5845689410.

The spelling of 78724442 in words is "seventy-eight million, seven hundred twenty-four thousand, four hundred forty-two".