81031378 has 4 divisors (see below), whose sum is σ = 121547070. Its totient is φ = 40515688.

The previous prime is 81031351. The next prime is 81031381. The reversal of 81031378 is 87313018.

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., 76160529 + 4870849 = 8727^2 + 2207^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20257843 + ... + 20257846.

Almost surely, 2^81031378 is an apocalyptic number.

81031378 is a deficient number, since it is larger than the sum of its proper divisors (40515692).

81031378 is a wasteful number, since it uses less digits than its factorization.

81031378 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40515691.

The product of its (nonzero) digits is 4032, while the sum is 31.

The square root of 81031378 is about 9001.7430534314. The cubic root of 81031378 is about 432.7307341350.

The spelling of 81031378 in words is "eighty-one million, thirty-one thousand, three hundred seventy-eight".