78664511 has 4 divisors (see below), whose sum is σ = 80338272. Its totient is φ = 76990752.

The previous prime is 78664493. The next prime is 78664517. The reversal of 78664511 is 11546687.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 11546687 = 389 ⋅29683.

It is a cyclic number.

It is not a de Polignac number, because 78664511 - 2¹⁸ = 78402367 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78664517) 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, 836810 + ... + 836903.

It is an arithmetic number, because the mean of its divisors is an integer number (20084568).

Almost surely, 2^78664511 is an apocalyptic number.

78664511 is a deficient number, since it is larger than the sum of its proper divisors (1673761).

78664511 is a wasteful number, since it uses less digits than its factorization.

78664511 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1673760.

The product of its digits is 40320, while the sum is 38.

The square root of 78664511 is about 8869.3016072293. The cubic root of 78664511 is about 428.4757843339.

The spelling of 78664511 in words is "seventy-eight million, six hundred sixty-four thousand, five hundred eleven".