81401578 has 4 divisors (see below), whose sum is σ = 122102370. Its totient is φ = 40700788.

The previous prime is 81401569. The next prime is 81401581. The reversal of 81401578 is 87510418.

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., 77211369 + 4190209 = 8787^2 + 2047^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20350393 + ... + 20350396.

Almost surely, 2^81401578 is an apocalyptic number.

81401578 is a deficient number, since it is larger than the sum of its proper divisors (40700792).

81401578 is a wasteful number, since it uses less digits than its factorization.

81401578 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40700791.

The product of its (nonzero) digits is 8960, while the sum is 34.

The square root of 81401578 is about 9022.2823054923. The cubic root of 81401578 is about 433.3887244117.

The spelling of 81401578 in words is "eighty-one million, four hundred one thousand, five hundred seventy-eight".