81778340 has 96 divisors (see below), whose sum is σ = 207567360. Its totient is φ = 26459136.

The previous prime is 81778327. The next prime is 81778343. The reversal of 81778340 is 4387718.

It is a junction number, because it is equal to n+sod(n) for n = 81778294 and 81778303.

It is not an unprimeable number, because it can be changed into a prime (81778343) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 350864 + ... + 351096.

It is an arithmetic number, because the mean of its divisors is an integer number (2162160).

Almost surely, 2^81778340 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81778340, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (103783680).

81778340 is an abundant number, since it is smaller than the sum of its proper divisors (125789020).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81778340 is a wasteful number, since it uses less digits than its factorization.

81778340 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 381 (or 379 counting only the distinct ones).

The product of its (nonzero) digits is 37632, while the sum is 38.

The square root of 81778340 is about 9043.1377297927. The cubic root of 81778340 is about 434.0563328096.

The spelling of 81778340 in words is "eighty-one million, seven hundred seventy-eight thousand, three hundred forty".