81008778 has 16 divisors (see below), whose sum is σ = 162118656. Its totient is φ = 26986080.

The previous prime is 81008773. The next prime is 81008801. The reversal of 81008778 is 87780018.

It is a happy number.

It is a super-2 number, since 2×81008778² = 13124844226106568, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81008773) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9783 + ... + 16053.

It is an arithmetic number, because the mean of its divisors is an integer number (10132416).

Almost surely, 2^81008778 is an apocalyptic number.

81008778 is an abundant number, since it is smaller than the sum of its proper divisors (81109878).

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

81008778 is a wasteful number, since it uses less digits than its factorization.

81008778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8429.

The product of its (nonzero) digits is 25088, while the sum is 39.

The square root of 81008778 is about 9000.4876534552. The cubic root of 81008778 is about 432.6905002397.

The spelling of 81008778 in words is "eighty-one million, eight thousand, seven hundred seventy-eight".