81551583 has 32 divisors (see below), whose sum is σ = 129185280. Its totient is φ = 50719680.

The previous prime is 81551581. The next prime is 81551633. The reversal of 81551583 is 38515518.

It is not a de Polignac number, because 81551583 - 2¹ = 81551581 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81551581) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 23860 + ... + 27062.

It is an arithmetic number, because the mean of its divisors is an integer number (4037040).

Almost surely, 2^81551583 is an apocalyptic number.

81551583 is a deficient number, since it is larger than the sum of its proper divisors (47633697).

81551583 is a wasteful number, since it uses less digits than its factorization.

81551583 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3276 (or 3270 counting only the distinct ones).

The product of its digits is 24000, while the sum is 36.

The square root of 81551583 is about 9030.5915088659. The cubic root of 81551583 is about 433.6547740582.

The spelling of 81551583 in words is "eighty-one million, five hundred fifty-one thousand, five hundred eighty-three".