81520508 has 48 divisors (see below), whose sum is σ = 158850720. Its totient is φ = 36427776.

The previous prime is 81520501. The next prime is 81520553. The reversal of 81520508 is 80502518.

It is a Harshad number since it is a multiple of its sum of digits (29).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81520501) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 131816 + ... + 132432.

It is an arithmetic number, because the mean of its divisors is an integer number (3309390).

Almost surely, 2^81520508 is an apocalyptic number.

It is an amenable number.

81520508 is a deficient number, since it is larger than the sum of its proper divisors (77330212).

81520508 is a wasteful number, since it uses less digits than its factorization.

81520508 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 734 (or 732 counting only the distinct ones).

The product of its (nonzero) digits is 3200, while the sum is 29.

The square root of 81520508 is about 9028.8708042590. The cubic root of 81520508 is about 433.5996860857.

It can be divided in two parts, 81520 and 508, that added together give a palindrome (82028).

The spelling of 81520508 in words is "eighty-one million, five hundred twenty thousand, five hundred eight".