78161691 has 8 divisors (see below), whose sum is σ = 104515600. Its totient is φ = 51957792.

The previous prime is 78161689. The next prime is 78161693. The reversal of 78161691 is 19616187.

It is an interprime number because it is at equal distance from previous prime (78161689) and next prime (78161693).

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 78161691 - 2¹ = 78161689 is a prime.

It is a super-2 number, since 2×78161691² = 12218499879958962, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78161693) 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 7 ways as a sum of consecutive naturals, for example, 36280 + ... + 38373.

It is an arithmetic number, because the mean of its divisors is an integer number (13064450).

Almost surely, 2^78161691 is an apocalyptic number.

78161691 is a deficient number, since it is larger than the sum of its proper divisors (26353909).

78161691 is a wasteful number, since it uses less digits than its factorization.

78161691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 75005.

The product of its digits is 18144, while the sum is 39.

The square root of 78161691 is about 8840.9100775882. The cubic root of 78161691 is about 427.5608996378.

The spelling of 78161691 in words is "seventy-eight million, one hundred sixty-one thousand, six hundred ninety-one".