81799515 has 24 divisors (see below), whose sum is σ = 162041568. Its totient is φ = 37393920.

The previous prime is 81799513. The next prime is 81799519. The reversal of 81799515 is 51599718.

It is not a de Polignac number, because 81799515 - 2¹ = 81799513 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is not an unprimeable number, because it can be changed into a prime (81799513) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 129526 + ... + 130155.

It is an arithmetic number, because the mean of its divisors is an integer number (6751732).

Almost surely, 2^81799515 is an apocalyptic number.

81799515 is a deficient number, since it is larger than the sum of its proper divisors (80242053).

81799515 is a wasteful number, since it uses less digits than its factorization.

81799515 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 259699 (or 259696 counting only the distinct ones).

The product of its digits is 113400, while the sum is 45.

The square root of 81799515 is about 9044.3084312732. The cubic root of 81799515 is about 434.0937932165.

The spelling of 81799515 in words is "eighty-one million, seven hundred ninety-nine thousand, five hundred fifteen".