81381015 has 48 divisors (see below), whose sum is σ = 149722560. Its totient is φ = 40803840.

The previous prime is 81381011. The next prime is 81381031. The reversal of 81381015 is 51018318.

It is not a de Polignac number, because 81381015 - 2² = 81381011 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81381015.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81381011) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 62491 + ... + 63779.

It is an arithmetic number, because the mean of its divisors is an integer number (3119220).

Almost surely, 2^81381015 is an apocalyptic number.

81381015 is a deficient number, since it is larger than the sum of its proper divisors (68341545).

81381015 is a wasteful number, since it uses less digits than its factorization.

81381015 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1384 (or 1381 counting only the distinct ones).

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

The square root of 81381015 is about 9021.1426659820. The cubic root of 81381015 is about 433.3522283017.

The spelling of 81381015 in words is "eighty-one million, three hundred eighty-one thousand, fifteen".