78391011 has 4 divisors (see below), whose sum is σ = 104521352. Its totient is φ = 52260672.

The previous prime is 78391009. The next prime is 78391043. The reversal of 78391011 is 11019387.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 78391011 - 2¹ = 78391009 is a prime.

It is a super-2 number, since 2×78391011² = 12290301211204242, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 78391011.

It is not an unprimeable number, because it can be changed into a prime (78391211) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13065166 + ... + 13065171.

It is an arithmetic number, because the mean of its divisors is an integer number (26130338).

Almost surely, 2^78391011 is an apocalyptic number.

78391011 is a deficient number, since it is larger than the sum of its proper divisors (26130341).

78391011 is a wasteful number, since it uses less digits than its factorization.

78391011 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26130340.

The product of its (nonzero) digits is 1512, while the sum is 30.

The square root of 78391011 is about 8853.8698318871. The cubic root of 78391011 is about 427.9786342582.

The spelling of 78391011 in words is "seventy-eight million, three hundred ninety-one thousand, eleven".