78669591 has 128 divisors (see below), whose sum is σ = 157925376. Its totient is φ = 33454080.

The previous prime is 78669581. The next prime is 78669601. The reversal of 78669591 is 19596687.

It is an interprime number because it is at equal distance from previous prime (78669581) and next prime (78669601).

It is not a de Polignac number, because 78669591 - 2⁵ = 78669559 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (51).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78669541) 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 127 ways as a sum of consecutive naturals, for example, 1174140 + ... + 1174206.

It is an arithmetic number, because the mean of its divisors is an integer number (1233792).

Almost surely, 2^78669591 is an apocalyptic number.

78669591 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

78669591 is a wasteful number, since it uses less digits than its factorization.

78669591 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 141.

The product of its digits is 816480, while the sum is 51.

The square root of 78669591 is about 8869.5879836664. The cubic root of 78669591 is about 428.4850075109.

The spelling of 78669591 in words is "seventy-eight million, six hundred sixty-nine thousand, five hundred ninety-one".