81605694 has 16 divisors (see below), whose sum is σ = 164404368. Its totient is φ = 27003072.

The previous prime is 81605659. The next prime is 81605707. The reversal of 81605694 is 49650618.

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, 48817 + ... + 50460.

It is an arithmetic number, because the mean of its divisors is an integer number (10275273).

Almost surely, 2^81605694 is an apocalyptic number.

81605694 is an abundant number, since it is smaller than the sum of its proper divisors (82798674).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81605694 is a wasteful number, since it uses less digits than its factorization.

81605694 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 99419.

The product of its (nonzero) digits is 51840, while the sum is 39.

The square root of 81605694 is about 9033.5869952085. The cubic root of 81605694 is about 433.7506655362.

The spelling of 81605694 in words is "eighty-one million, six hundred five thousand, six hundred ninety-four".