81620537182736 has 10 divisors (see below), whose sum is σ = 158139790791582. Its totient is φ = 40810268591360.

The previous prime is 81620537182693. The next prime is 81620537182739. The reversal of 81620537182736 is 63728173502618.

It can be written as a sum of positive squares in only one way, i.e., 46739701182736 + 34880836000000 = 6836644^2 + 5906000^2 .

It is not an unprimeable number, because it can be changed into a prime (81620537182739) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2550641786945 + ... + 2550641786976.

Almost surely, 2^{81620537182736} is an apocalyptic number.

It is an amenable number.

81620537182736 is a deficient number, since it is larger than the sum of its proper divisors (76519253608846).

81620537182736 is a wasteful number, since it uses less digits than its factorization.

81620537182736 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5101283573929 (or 5101283573923 counting only the distinct ones).

The product of its (nonzero) digits is 20321280, while the sum is 59.

The spelling of 81620537182736 in words is "eighty-one trillion, six hundred twenty billion, five hundred thirty-seven million, one hundred eighty-two thousand, seven hundred thirty-six".