81381510 has 160 divisors (see below), whose sum is σ = 258711552. Its totient is φ = 17962560.

The previous prime is 81381497. The next prime is 81381539. The reversal of 81381510 is 1518318.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 175539 + ... + 176001.

Almost surely, 2^81381510 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81381510, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (129355776).

81381510 is an abundant number, since it is smaller than the sum of its proper divisors (177330042).

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

81381510 is a wasteful number, since it uses less digits than its factorization.

81381510 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 520 (or 511 counting only the distinct ones).

The product of its (nonzero) digits is 960, while the sum is 27.

The square root of 81381510 is about 9021.1701014891. The cubic root of 81381510 is about 433.3531069215.

Adding to 81381510 its reverse (1518318), we get a palindrome (82899828).

The spelling of 81381510 in words is "eighty-one million, three hundred eighty-one thousand, five hundred ten".