391678638593 has 4 divisors (see below), whose sum is σ = 427285787568. Its totient is φ = 356071489620.

The previous prime is 391678638557. The next prime is 391678638613. The reversal of 391678638593 is 395836876193.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 391678638593 - 2¹⁶ = 391678573057 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (391678638193) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 17803574471 + ... + 17803574492.

It is an arithmetic number, because the mean of its divisors is an integer number (106821446892).

Almost surely, 2^391678638593 is an apocalyptic number.

It is an amenable number.

391678638593 is a deficient number, since it is larger than the sum of its proper divisors (35607148975).

391678638593 is a wasteful number, since it uses less digits than its factorization.

391678638593 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35607148974.

The product of its digits is 176359680, while the sum is 68.

The spelling of 391678638593 in words is "three hundred ninety-one billion, six hundred seventy-eight million, six hundred thirty-eight thousand, five hundred ninety-three".