81681674 has 4 divisors (see below), whose sum is σ = 122522514. Its totient is φ = 40840836.

The previous prime is 81681659. The next prime is 81681679. The reversal of 81681674 is 47618618.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 47618618 = 2 ⋅23809309.

It can be written as a sum of positive squares in only one way, i.e., 47541025 + 34140649 = 6895^2 + 5843^2 .

It is not an unprimeable number, because it can be changed into a prime (81681679) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20420417 + ... + 20420420.

Almost surely, 2^81681674 is an apocalyptic number.

81681674 is a deficient number, since it is larger than the sum of its proper divisors (40840840).

81681674 is a wasteful number, since it uses less digits than its factorization.

81681674 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40840839.

The product of its digits is 64512, while the sum is 41.

The square root of 81681674 is about 9037.7914337519. The cubic root of 81681674 is about 433.8852401028.

The spelling of 81681674 in words is "eighty-one million, six hundred eighty-one thousand, six hundred seventy-four".