78171998469049 has 3 divisors (see below), whose sum is σ = 78172007310543. Its totient is φ = 78171989627556.

The previous prime is 78171998469011. The next prime is 78171998469053. The reversal of 78171998469049 is 94096489917187.

The square root of 78171998469049 is 8841493.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in only one way, i.e., 16992426025 + 78155006043024 = 130355^2 + 8840532^2 .

It is not a de Polignac number, because 78171998469049 - 2¹¹ = 78171998467001 is a prime.

It is a super-2 number, since 2×78171998469049² (a number of 29 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78171998469079) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 4420747 + ... + 13262239.

It is an arithmetic number, because the mean of its divisors is an integer number (26057335770181).

Almost surely, 2^{78171998469049} is an apocalyptic number.

78171998469049 is the 8841493-rd square number.

78171998469049 is the 4420747-th centered octagonal number.

It is an amenable number.

78171998469049 is a deficient number, since it is larger than the sum of its proper divisors (8841494).

78171998469049 is an frugal number, since it uses more digits than its factorization.

78171998469049 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17682986 (or 8841493 counting only the distinct ones).

The product of its (nonzero) digits is 1975228416, while the sum is 82.

The spelling of 78171998469049 in words is "seventy-eight trillion, one hundred seventy-one billion, nine hundred ninety-eight million, four hundred sixty-nine thousand, forty-nine".