81698815 has 8 divisors (see below), whose sum is σ = 106951248. Its totient is φ = 59417280.

The previous prime is 81698807. The next prime is 81698863. The reversal of 81698815 is 51889618.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 81698815 - 2³ = 81698807 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 742662 + ... + 742771.

It is an arithmetic number, because the mean of its divisors is an integer number (13368906).

Almost surely, 2^81698815 is an apocalyptic number.

81698815 is a deficient number, since it is larger than the sum of its proper divisors (25252433).

81698815 is a wasteful number, since it uses less digits than its factorization.

81698815 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1485449.

The product of its digits is 138240, while the sum is 46.

The square root of 81698815 is about 9038.7396798448. The cubic root of 81698815 is about 433.9155884309.

It can be divided in two parts, 81 and 698815, that added together give a palindrome (698896).

The spelling of 81698815 in words is "eighty-one million, six hundred ninety-eight thousand, eight hundred fifteen".