81597987 has 12 divisors (see below), whose sum is σ = 121049760. Its totient is φ = 52928208.

The previous prime is 81597979. The next prime is 81598007. The reversal of 81597987 is 78979518.

It is not a de Polignac number, because 81597987 - 2³ = 81597979 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81597947) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 122187 + ... + 122852.

It is an arithmetic number, because the mean of its divisors is an integer number (10087480).

Almost surely, 2^81597987 is an apocalyptic number.

81597987 is a deficient number, since it is larger than the sum of its proper divisors (39451773).

81597987 is a wasteful number, since it uses less digits than its factorization.

81597987 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 245082 (or 245079 counting only the distinct ones).

The product of its digits is 1270080, while the sum is 54.

The square root of 81597987 is about 9033.1604103990. The cubic root of 81597987 is about 433.7370103549.

The spelling of 81597987 in words is "eighty-one million, five hundred ninety-seven thousand, nine hundred eighty-seven".