81516506 has 16 divisors (see below), whose sum is σ = 126851400. Its totient is φ = 39240768.

The previous prime is 81516493. The next prime is 81516509. The reversal of 81516506 is 60561518.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 31460881 + 50055625 = 5609^2 + 7075^2 .

It is not an unprimeable number, because it can be changed into a prime (81516509) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 20756 + ... + 24368.

Almost surely, 2^81516506 is an apocalyptic number.

81516506 is a deficient number, since it is larger than the sum of its proper divisors (45334894).

81516506 is a wasteful number, since it uses less digits than its factorization.

81516506 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4033.

The product of its (nonzero) digits is 7200, while the sum is 32.

The square root of 81516506 is about 9028.6491791408. The cubic root of 81516506 is about 433.5925905528.

The spelling of 81516506 in words is "eighty-one million, five hundred sixteen thousand, five hundred six".