81738949 has 4 divisors (see below), whose sum is σ = 81860364. Its totient is φ = 81617536.

The previous prime is 81738929. The next prime is 81738959. The reversal of 81738949 is 94983718.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 94983718 = 2 ⋅47491859.

It can be written as a sum of positive squares in 2 ways, for example, as 79121025 + 2617924 = 8895^2 + 1618^2 .

It is a cyclic number.

It is not a de Polignac number, because 81738949 - 2¹⁵ = 81706181 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81738929) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 59692 + ... + 61045.

It is an arithmetic number, because the mean of its divisors is an integer number (20465091).

Almost surely, 2^81738949 is an apocalyptic number.

It is an amenable number.

81738949 is a deficient number, since it is larger than the sum of its proper divisors (121415).

81738949 is a wasteful number, since it uses less digits than its factorization.

81738949 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 121414.

The product of its digits is 435456, while the sum is 49.

The square root of 81738949 is about 9040.9595176618. The cubic root of 81738949 is about 433.9866295158.

The spelling of 81738949 in words is "eighty-one million, seven hundred thirty-eight thousand, nine hundred forty-nine".