81556516 has 6 divisors (see below), whose sum is σ = 142723910. Its totient is φ = 40778256.

The previous prime is 81556513. The next prime is 81556537. The reversal of 81556516 is 61565518.

It can be written as a sum of positive squares in only one way, i.e., 81000000 + 556516 = 9000^2 + 746^2 .

It is not an unprimeable number, because it can be changed into a prime (81556513) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10194561 + ... + 10194568.

Almost surely, 2^81556516 is an apocalyptic number.

It is an amenable number.

81556516 is a deficient number, since it is larger than the sum of its proper divisors (61167394).

81556516 is a wasteful number, since it uses less digits than its factorization.

81556516 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20389133 (or 20389131 counting only the distinct ones).

The product of its digits is 36000, while the sum is 37.

The square root of 81556516 is about 9030.8646319165. The cubic root of 81556516 is about 433.6635177098.

It can be divided in two parts, 81 and 556516, that multiplied together give a square (45077796 = 6714²).

The spelling of 81556516 in words is "eighty-one million, five hundred fifty-six thousand, five hundred sixteen".