78481781 has 12 divisors (see below), whose sum is σ = 91809900. Its totient is φ = 66890880.

The previous prime is 78481721. The next prime is 78481829. The reversal of 78481781 is 18718487.

It can be written as a sum of positive squares in 2 ways, for example, as 442225 + 78039556 = 665^2 + 8834^2 .

It is not a de Polignac number, because 78481781 - 2⁶ = 78481717 is a prime.

It is a super-2 number, since 2×78481781² = 12318779897863922, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78481721) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 4445 + ... + 13293.

It is an arithmetic number, because the mean of its divisors is an integer number (7650825).

Almost surely, 2^78481781 is an apocalyptic number.

It is an amenable number.

78481781 is a deficient number, since it is larger than the sum of its proper divisors (13328119).

78481781 is a wasteful number, since it uses less digits than its factorization.

78481781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9044 (or 9037 counting only the distinct ones).

The product of its digits is 100352, while the sum is 44.

The square root of 78481781 is about 8858.9943560203. The cubic root of 78481781 is about 428.1437579364.

The spelling of 78481781 in words is "seventy-eight million, four hundred eighty-one thousand, seven hundred eighty-one".