78240165261 has 16 divisors (see below), whose sum is σ = 107043678720. Its totient is φ = 50805140400.

The previous prime is 78240165251. The next prime is 78240165307. The reversal of 78240165261 is 16256104287.

It is a happy number.

It is not a de Polignac number, because 78240165261 - 2³³ = 69650230669 is a prime.

It is a super-2 number, since 2×78240165261² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78240165221) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 798415 + ... + 891036.

It is an arithmetic number, because the mean of its divisors is an integer number (6690229920).

Almost surely, 2^78240165261 is an apocalyptic number.

It is an amenable number.

78240165261 is a deficient number, since it is larger than the sum of its proper divisors (28803513459).

78240165261 is a wasteful number, since it uses less digits than its factorization.

78240165261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1689856.

The product of its (nonzero) digits is 161280, while the sum is 42.

The spelling of 78240165261 in words is "seventy-eight billion, two hundred forty million, one hundred sixty-five thousand, two hundred sixty-one".