81077578 has 4 divisors (see below), whose sum is σ = 121616370. Its totient is φ = 40538788.

The previous prime is 81077561. The next prime is 81077609. The reversal of 81077578 is 87577018.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 40666129 + 40411449 = 6377^2 + 6357^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20269393 + ... + 20269396.

Almost surely, 2^81077578 is an apocalyptic number.

81077578 is a deficient number, since it is larger than the sum of its proper divisors (40538792).

81077578 is a wasteful number, since it uses less digits than its factorization.

81077578 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40538791.

The product of its (nonzero) digits is 109760, while the sum is 43.

The square root of 81077578 is about 9004.3088574304. The cubic root of 81077578 is about 432.8129589147.

The spelling of 81077578 in words is "eighty-one million, seventy-seven thousand, five hundred seventy-eight".