81061636 has 6 divisors (see below), whose sum is σ = 141857870. Its totient is φ = 40530816.

The previous prime is 81061553. The next prime is 81061681. The reversal of 81061636 is 63616018.

It can be written as a sum of positive squares in only one way, i.e., 53436100 + 27625536 = 7310^2 + 5256^2 .

It is a junction number, because it is equal to n+sod(n) for n = 81061598 and 81061607.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10132701 + ... + 10132708.

Almost surely, 2^81061636 is an apocalyptic number.

It is an amenable number.

81061636 is a deficient number, since it is larger than the sum of its proper divisors (60796234).

81061636 is a wasteful number, since it uses less digits than its factorization.

81061636 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20265413 (or 20265411 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 31.

The square root of 81061636 is about 9003.4235710645. The cubic root of 81061636 is about 432.7845895568.

The spelling of 81061636 in words is "eighty-one million, sixty-one thousand, six hundred thirty-six".