78518981 has 4 divisors (see below), whose sum is σ = 78550464. Its totient is φ = 78487500.

The previous prime is 78518959. The next prime is 78518983. The reversal of 78518981 is 18981587.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 18981587 = 109 ⋅174143.

It is a cyclic number.

It is not a de Polignac number, because 78518981 - 2¹⁸ = 78256837 is a prime.

It is a super-2 number, since 2×78518981² = 12330460754556722, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78518983) 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 3 ways as a sum of consecutive naturals, for example, 11645 + ... + 17106.

It is an arithmetic number, because the mean of its divisors is an integer number (19637616).

Almost surely, 2^78518981 is an apocalyptic number.

It is an amenable number.

78518981 is a deficient number, since it is larger than the sum of its proper divisors (31483).

78518981 is a wasteful number, since it uses less digits than its factorization.

78518981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31482.

The product of its digits is 161280, while the sum is 47.

The square root of 78518981 is about 8861.0936683911. The cubic root of 78518981 is about 428.2113933027.

The spelling of 78518981 in words is "seventy-eight million, five hundred eighteen thousand, nine hundred eighty-one".