81637441 has 4 divisors (see below), whose sum is σ = 81788884. Its totient is φ = 81486000.

The previous prime is 81637427. The next prime is 81637447. The reversal of 81637441 is 14473618.

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: 14473618 = 2 ⋅7236809.

It can be written as a sum of positive squares in 2 ways, for example, as 46294416 + 35343025 = 6804^2 + 5945^2 .

It is a cyclic number.

It is not a de Polignac number, because 81637441 - 2⁷ = 81637313 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81637397 and 81637406.

It is not an unprimeable number, because it can be changed into a prime (81637447) 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, 74910 + ... + 75991.

It is an arithmetic number, because the mean of its divisors is an integer number (20447221).

Almost surely, 2^81637441 is an apocalyptic number.

It is an amenable number.

81637441 is a deficient number, since it is larger than the sum of its proper divisors (151443).

81637441 is a wasteful number, since it uses less digits than its factorization.

81637441 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 151442.

The product of its digits is 16128, while the sum is 34.

The square root of 81637441 is about 9035.3439890244. The cubic root of 81637441 is about 433.8069054724.

The spelling of 81637441 in words is "eighty-one million, six hundred thirty-seven thousand, four hundred forty-one".