81605698 has 8 divisors (see below), whose sum is σ = 122446908. Its totient is φ = 40790064.

The previous prime is 81605659. The next prime is 81605707. The reversal of 81605698 is 89650618.

It can be written as a sum of positive squares in 2 ways, for example, as 81595089 + 10609 = 9033^2 + 103^2 .

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

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8940 + ... + 15592.

Almost surely, 2^81605698 is an apocalyptic number.

81605698 is a deficient number, since it is larger than the sum of its proper divisors (40841210).

81605698 is a wasteful number, since it uses less digits than its factorization.

81605698 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12788.

The product of its (nonzero) digits is 103680, while the sum is 43.

The square root of 81605698 is about 9033.5872166045. The cubic root of 81605698 is about 433.7506726231.

The spelling of 81605698 in words is "eighty-one million, six hundred five thousand, six hundred ninety-eight".