81660842207524 has 6 divisors (see below), whose sum is σ = 142906473863174. Its totient is φ = 40830421103760.

The previous prime is 81660842207471. The next prime is 81660842207591. The reversal of 81660842207524 is 42570224806618.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 77258474502400 + 4402367705124 = 8789680^2 + 2098182^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10207605275937 + ... + 10207605275944.

Almost surely, 2^{81660842207524} is an apocalyptic number.

It is an amenable number.

81660842207524 is a deficient number, since it is larger than the sum of its proper divisors (61245631655650).

81660842207524 is a wasteful number, since it uses less digits than its factorization.

81660842207524 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20415210551885 (or 20415210551883 counting only the distinct ones).

The product of its (nonzero) digits is 10321920, while the sum is 55.

The spelling of 81660842207524 in words is "eighty-one trillion, six hundred sixty billion, eight hundred forty-two million, two hundred seven thousand, five hundred twenty-four".