81749461 has 4 divisors (see below), whose sum is σ = 81834624. Its totient is φ = 81664300.

The previous prime is 81749453. The next prime is 81749467. The reversal of 81749461 is 16494718.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 16494718 = 2 ⋅8247359.

It is a cyclic number.

It is not a de Polignac number, because 81749461 - 2³ = 81749453 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81749467) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 41125 + ... + 43066.

It is an arithmetic number, because the mean of its divisors is an integer number (20458656).

Almost surely, 2^81749461 is an apocalyptic number.

81749461 is the 4044-th centered decagonal number.

It is an amenable number.

81749461 is a deficient number, since it is larger than the sum of its proper divisors (85163).

81749461 is an equidigital number, since it uses as much as digits as its factorization.

81749461 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 85162.

The product of its digits is 48384, while the sum is 40.

The square root of 81749461 is about 9041.5408531953. The cubic root of 81749461 is about 434.0052329354.

The spelling of 81749461 in words is "eighty-one million, seven hundred forty-nine thousand, four hundred sixty-one".