81510449 has 4 divisors (see below), whose sum is σ = 83048436. Its totient is φ = 79972464.

The previous prime is 81510433. The next prime is 81510463. The reversal of 81510449 is 94401518.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 63600625 + 17909824 = 7975^2 + 4232^2 .

It is a cyclic number.

It is not a de Polignac number, because 81510449 - 2⁴ = 81510433 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81510409) 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, 768914 + ... + 769019.

It is an arithmetic number, because the mean of its divisors is an integer number (20762109).

Almost surely, 2^81510449 is an apocalyptic number.

It is an amenable number.

81510449 is a deficient number, since it is larger than the sum of its proper divisors (1537987).

81510449 is a wasteful number, since it uses less digits than its factorization.

81510449 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1537986.

The product of its (nonzero) digits is 5760, while the sum is 32.

The square root of 81510449 is about 9028.3137406716. The cubic root of 81510449 is about 433.5818510698.

The spelling of 81510449 in words is "eighty-one million, five hundred ten thousand, four hundred forty-nine".