78138642 has 16 divisors (see below), whose sum is σ = 159226560. Its totient is φ = 25554672.

The previous prime is 78138617. The next prime is 78138667. The reversal of 78138642 is 24683187.

It is an interprime number because it is at equal distance from previous prime (78138617) and next prime (78138667).

It is a super-2 number, since 2×78138642² = 12211294747208328, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 78138642.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 122542 + ... + 123177.

It is an arithmetic number, because the mean of its divisors is an integer number (9951660).

Almost surely, 2^78138642 is an apocalyptic number.

78138642 is an abundant number, since it is smaller than the sum of its proper divisors (81087918).

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

78138642 is a wasteful number, since it uses less digits than its factorization.

78138642 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 245777.

The product of its digits is 64512, while the sum is 39.

The square root of 78138642 is about 8839.6064392030. The cubic root of 78138642 is about 427.5188678790.

The spelling of 78138642 in words is "seventy-eight million, one hundred thirty-eight thousand, six hundred forty-two".