81551582 has 12 divisors (see below), whose sum is σ = 142299360. Its totient is φ = 34950636.

The previous prime is 81551581. The next prime is 81551633. The reversal of 81551582 is 28515518.

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 5 ways as a sum of consecutive naturals, for example, 415982 + ... + 416177.

It is an arithmetic number, because the mean of its divisors is an integer number (11858280).

Almost surely, 2^81551582 is an apocalyptic number.

81551582 is a deficient number, since it is larger than the sum of its proper divisors (60747778).

81551582 is a wasteful number, since it uses less digits than its factorization.

81551582 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 832175 (or 832168 counting only the distinct ones).

The product of its digits is 16000, while the sum is 35.

The square root of 81551582 is about 9030.5914534985. The cubic root of 81551582 is about 433.6547722857.

The spelling of 81551582 in words is "eighty-one million, five hundred fifty-one thousand, five hundred eighty-two".