78161172521 has 8 divisors (see below), whose sum is σ = 78485461704. Its totient is φ = 77837372800.

The previous prime is 78161172473. The next prime is 78161172553. The reversal of 78161172521 is 12527116187.

It can be written as a sum of positive squares in 4 ways, for example, as 5794254400 + 72366918121 = 76120^2 + 269011^2 .

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-78161172521 is a prime.

It is a super-2 number, since 2×78161172521² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78161172571) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 199421 + ... + 442821.

It is an arithmetic number, because the mean of its divisors is an integer number (9810682713).

Almost surely, 2^78161172521 is an apocalyptic number.

It is an amenable number.

78161172521 is a deficient number, since it is larger than the sum of its proper divisors (324289183).

78161172521 is a wasteful number, since it uses less digits than its factorization.

78161172521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 244731.

The product of its digits is 47040, while the sum is 41.

The spelling of 78161172521 in words is "seventy-eight billion, one hundred sixty-one million, one hundred seventy-two thousand, five hundred twenty-one".