81510000 has 400 divisors, whose sum is σ = 325395840. Its totient is φ = 17280000.

The previous prime is 81509971. The next prime is 81510007. The reversal of 81510000 is 1518.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (400).

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81510007) by changing a digit.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 4289991 + ... + 4290009.

Almost surely, 2^81510000 is an apocalyptic number.

81510000 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 81510000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (162697920).

81510000 is an abundant number, since it is smaller than the sum of its proper divisors (243885840).

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

81510000 is a wasteful number, since it uses less digits than its factorization.

81510000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 74 (or 53 counting only the distinct ones).

The product of its (nonzero) digits is 40, while the sum is 15.

The square root of 81510000 is about 9028.2888744213. The cubic root of 81510000 is about 433.5810549404.

Adding to 81510000 its reverse (1518), we get a palindrome (81511518).

The spelling of 81510000 in words is "eighty-one million, five hundred ten thousand".