78634646578 has 4 divisors (see below), whose sum is σ = 117951969870. Its totient is φ = 39317323288.

The previous prime is 78634646501. The next prime is 78634646611. The reversal of 78634646578 is 87564643687.

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., 78504754969 + 129891609 = 280187^2 + 11397^2 .

It is a super-2 number, since 2×78634646578² (a number of 23 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 19658661643 + ... + 19658661646.

Almost surely, 2^78634646578 is an apocalyptic number.

78634646578 is a deficient number, since it is larger than the sum of its proper divisors (39317323292).

78634646578 is a wasteful number, since it uses less digits than its factorization.

78634646578 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39317323291.

The product of its digits is 162570240, while the sum is 64.

The spelling of 78634646578 in words is "seventy-eight billion, six hundred thirty-four million, six hundred forty-six thousand, five hundred seventy-eight".