78142779 has 64 divisors (see below), whose sum is σ = 139937280. Its totient is φ = 42456960.

The previous prime is 78142747. The next prime is 78142783. The reversal of 78142779 is 97724187.

It is a happy number.

It is not a de Polignac number, because 78142779 - 2⁵ = 78142747 is a prime.

It is a super-2 number, since 2×78142779² = 12212587819685682, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (78142789) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 142584 + ... + 143130.

It is an arithmetic number, because the mean of its divisors is an integer number (2186520).

Almost surely, 2^78142779 is an apocalyptic number.

78142779 is a deficient number, since it is larger than the sum of its proper divisors (61794501).

78142779 is a wasteful number, since it uses less digits than its factorization.

78142779 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 617 (or 611 counting only the distinct ones).

The product of its digits is 197568, while the sum is 45.

The square root of 78142779 is about 8839.8404397365. The cubic root of 78142779 is about 427.5264126494.

The spelling of 78142779 in words is "seventy-eight million, one hundred forty-two thousand, seven hundred seventy-nine".