81137047 has 4 divisors (see below), whose sum is σ = 81311256. Its totient is φ = 80962840.

The previous prime is 81137033. The next prime is 81137053. The reversal of 81137047 is 74073118.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 81137047 - 2²³ = 72748439 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81137347) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 86404 + ... + 87337.

It is an arithmetic number, because the mean of its divisors is an integer number (20327814).

Almost surely, 2^81137047 is an apocalyptic number.

81137047 is a deficient number, since it is larger than the sum of its proper divisors (174209).

81137047 is a wasteful number, since it uses less digits than its factorization.

81137047 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 174208.

The product of its (nonzero) digits is 4704, while the sum is 31.

The square root of 81137047 is about 9007.6105044568. The cubic root of 81137047 is about 432.9187533239.

The spelling of 81137047 in words is "eighty-one million, one hundred thirty-seven thousand, forty-seven".