81693693 has 12 divisors (see below), whose sum is σ = 118109628. Its totient is φ = 54412800.

The previous prime is 81693683. The next prime is 81693697. The reversal of 81693693 is 39639618.

It can be written as a sum of positive squares in 2 ways, for example, as 5008644 + 76685049 = 2238^2 + 8757^2 .

It is not a de Polignac number, because 81693693 - 2¹⁰ = 81692669 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81693697) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 8221 + ... + 15197.

It is an arithmetic number, because the mean of its divisors is an integer number (9842469).

Almost surely, 2^81693693 is an apocalyptic number.

It is an amenable number.

81693693 is a deficient number, since it is larger than the sum of its proper divisors (36415935).

81693693 is a wasteful number, since it uses less digits than its factorization.

81693693 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8284 (or 8281 counting only the distinct ones).

The product of its digits is 209952, while the sum is 45.

The square root of 81693693 is about 9038.4563394420. The cubic root of 81693693 is about 433.9065203185.

The spelling of 81693693 in words is "eighty-one million, six hundred ninety-three thousand, six hundred ninety-three".