81361688 has 8 divisors (see below), whose sum is σ = 152553180. Its totient is φ = 40680840.

The previous prime is 81361627. The next prime is 81361691. The reversal of 81361688 is 88616318.

It is a tau number, because it is divible by the number of its divisors (8).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5085098 + ... + 5085113.

Almost surely, 2^81361688 is an apocalyptic number.

It is an amenable number.

81361688 is a deficient number, since it is larger than the sum of its proper divisors (71191492).

81361688 is a wasteful number, since it uses less digits than its factorization.

81361688 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10170217 (or 10170213 counting only the distinct ones).

The product of its digits is 55296, while the sum is 41.

The square root of 81361688 is about 9020.0713966132. The cubic root of 81361688 is about 433.3179202933.

The spelling of 81361688 in words is "eighty-one million, three hundred sixty-one thousand, six hundred eighty-eight".