81436778 has 16 divisors (see below), whose sum is σ = 126977760. Its totient is φ = 39137616.

The previous prime is 81436777. The next prime is 81436801. The reversal of 81436778 is 87763418.

It is a super-2 number, since 2×81436778² = 13263897622042568, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81436777) 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, 488 + ... + 12771.

It is an arithmetic number, because the mean of its divisors is an integer number (7936110).

Almost surely, 2^81436778 is an apocalyptic number.

81436778 is a deficient number, since it is larger than the sum of its proper divisors (45540982).

81436778 is a wasteful number, since it uses less digits than its factorization.

81436778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13381.

The product of its digits is 225792, while the sum is 44.

The square root of 81436778 is about 9024.2328205782. The cubic root of 81436778 is about 433.4511846453.

The spelling of 81436778 in words is "eighty-one million, four hundred thirty-six thousand, seven hundred seventy-eight".