81687606 has 192 divisors, whose sum is σ = 234420480. Its totient is φ = 18627840.

The previous prime is 81687589. The next prime is 81687607. The reversal of 81687606 is 60678618.

It is a super-2 number, since 2×81687606² = 13345729948022472, which contains 22 as substring.

It is a hoax number, since the sum of its digits (42) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81687607) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 1219185 + ... + 1219251.

It is an arithmetic number, because the mean of its divisors is an integer number (1220940).

Almost surely, 2^81687606 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81687606, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (117210240).

81687606 is an abundant number, since it is smaller than the sum of its proper divisors (152732874).

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

81687606 is a wasteful number, since it uses less digits than its factorization.

81687606 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 139 (or 132 counting only the distinct ones).

The product of its (nonzero) digits is 96768, while the sum is 42.

The square root of 81687606 is about 9038.1196053161. The cubic root of 81687606 is about 433.8957432541.

The spelling of 81687606 in words is "eighty-one million, six hundred eighty-seven thousand, six hundred six".