81690000 has 200 divisors, whose sum is σ = 302153280. Its totient is φ = 18624000.

The previous prime is 81689989. The next prime is 81690001. The reversal of 81690000 is 9618.

It is a tau number, because it is divible by the number of its divisors (200).

It is a super-2 number, since 2×81690000² = 13346512200000000, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81690001) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 209806 + ... + 210194.

Almost surely, 2^81690000 is an apocalyptic number.

81690000 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81690000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (151076640).

81690000 is an abundant number, since it is smaller than the sum of its proper divisors (220463280).

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

81690000 is a wasteful number, since it uses less digits than its factorization.

81690000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 427 (or 406 counting only the distinct ones).

The product of its (nonzero) digits is 432, while the sum is 24.

The square root of 81690000 is about 9038.2520433987. The cubic root of 81690000 is about 433.8999819071.

Adding to 81690000 its reverse (9618), we get a palindrome (81699618).

The spelling of 81690000 in words is "eighty-one million, six hundred ninety thousand".