81312000 has 432 divisors, whose sum is σ = 339271296. Its totient is φ = 16896000.

The previous prime is 81311987. The next prime is 81312013. The reversal of 81312000 is 21318.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (81311987) and next prime (81312013).

It is a super-2 number, since 2×81312000² = 13223282688000000, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 7391995 + ... + 7392005.

Almost surely, 2^81312000 is an apocalyptic number.

81312000 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 81312000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (169635648).

81312000 is an abundant number, since it is smaller than the sum of its proper divisors (257959296).

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

81312000 is a wasteful number, since it uses less digits than its factorization.

81312000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 63 (or 28 counting only the distinct ones).

The product of its (nonzero) digits is 48, while the sum is 15.

The square root of 81312000 is about 9017.3166740444. The cubic root of 81312000 is about 433.2296925053.

Adding to 81312000 its reverse (21318), we get a palindrome (81333318).

The spelling of 81312000 in words is "eighty-one million, three hundred twelve thousand".