81691692 has 12 divisors (see below), whose sum is σ = 190613976. Its totient is φ = 27230560.

The previous prime is 81691691. The next prime is 81691717. The reversal of 81691692 is 29619618.

It is a tau number, because it is divible by the number of its divisors (12).

It is a super-3 number, since 3×81691692³ (a number of 25 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (81691691) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3403809 + ... + 3403832.

It is an arithmetic number, because the mean of its divisors is an integer number (15884498).

Almost surely, 2^81691692 is an apocalyptic number.

It is an amenable number.

81691692 is an abundant number, since it is smaller than the sum of its proper divisors (108922284).

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

81691692 is a wasteful number, since it uses less digits than its factorization.

81691692 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6807648 (or 6807646 counting only the distinct ones).

The product of its digits is 46656, while the sum is 42.

The square root of 81691692 is about 9038.3456450835. The cubic root of 81691692 is about 433.9029775969.

The spelling of 81691692 in words is "eighty-one million, six hundred ninety-one thousand, six hundred ninety-two".