81587398 has 4 divisors (see below), whose sum is σ = 122381100. Its totient is φ = 40793698.

The previous prime is 81587357. The next prime is 81587419. The reversal of 81587398 is 89378518.

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

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20396848 + ... + 20396851.

It is an arithmetic number, because the mean of its divisors is an integer number (30595275).

Almost surely, 2^81587398 is an apocalyptic number.

81587398 is a deficient number, since it is larger than the sum of its proper divisors (40793702).

81587398 is a wasteful number, since it uses less digits than its factorization.

81587398 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40793701.

The product of its digits is 483840, while the sum is 49.

The square root of 81587398 is about 9032.5742731516. The cubic root of 81587398 is about 433.7182474742.

The spelling of 81587398 in words is "eighty-one million, five hundred eighty-seven thousand, three hundred ninety-eight".