78391042 has 16 divisors (see below), whose sum is σ = 118816632. Its totient is φ = 38787840.

The previous prime is 78391009. The next prime is 78391043. The reversal of 78391042 is 24019387.

It can be written as a sum of positive squares in 4 ways, for example, as 38081241 + 40309801 = 6171^2 + 6349^2 .

It is a super-2 number, since 2×78391042² = 12290310931691528, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 78390989 and 78391007.

It is not an unprimeable number, because it can be changed into a prime (78391043) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 131898 + ... + 132490.

Almost surely, 2^78391042 is an apocalyptic number.

78391042 is a deficient number, since it is larger than the sum of its proper divisors (40425590).

78391042 is a wasteful number, since it uses less digits than its factorization.

78391042 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1173.

The product of its (nonzero) digits is 12096, while the sum is 34.

The square root of 78391042 is about 8853.8715825338. The cubic root of 78391042 is about 427.9786906734.

The spelling of 78391042 in words is "seventy-eight million, three hundred ninety-one thousand, forty-two".