81778416 has 20 divisors (see below), whose sum is σ = 211261032. Its totient is φ = 27259456.

The previous prime is 81778379. The next prime is 81778423. The reversal of 81778416 is 61487718.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 851811 + ... + 851906.

Almost surely, 2^81778416 is an apocalyptic number.

It is an amenable number.

81778416 is an abundant number, since it is smaller than the sum of its proper divisors (129482616).

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

81778416 is a wasteful number, since it uses less digits than its factorization.

81778416 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1703728 (or 1703722 counting only the distinct ones).

The product of its digits is 75264, while the sum is 42.

The square root of 81778416 is about 9043.1419318730. The cubic root of 81778416 is about 434.0564672718.

The spelling of 81778416 in words is "eighty-one million, seven hundred seventy-eight thousand, four hundred sixteen".