78105511 has 4 divisors (see below), whose sum is σ = 85206024. Its totient is φ = 71005000.

The previous prime is 78105491. The next prime is 78105529. The reversal of 78105511 is 11550187.

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

It is a de Polignac number, because none of the positive numbers 2^k-78105511 is a prime.

It is a super-2 number, since 2×78105511² = 12200941697142242, 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 78105511.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78105551) 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, 3550240 + ... + 3550261.

It is an arithmetic number, because the mean of its divisors is an integer number (21301506).

Almost surely, 2^78105511 is an apocalyptic number.

78105511 is a deficient number, since it is larger than the sum of its proper divisors (7100513).

78105511 is a wasteful number, since it uses less digits than its factorization.

78105511 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7100512.

The product of its (nonzero) digits is 1400, while the sum is 28.

The square root of 78105511 is about 8837.7322317436. The cubic root of 78105511 is about 427.4584362769.

Adding to 78105511 its reverse (11550187), we get a palindrome (89655698).

The spelling of 78105511 in words is "seventy-eight million, one hundred five thousand, five hundred eleven".