81187537 has 8 divisors (see below), whose sum is σ = 82595520. Its totient is φ = 79791600.

The previous prime is 81187531. The next prime is 81187549. The reversal of 81187537 is 73578118.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81187537 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81187537.

It is not an unprimeable number, because it can be changed into a prime (81187531) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11148 + ... + 16930.

It is an arithmetic number, because the mean of its divisors is an integer number (10324440).

Almost surely, 2^81187537 is an apocalyptic number.

It is an amenable number.

81187537 is a deficient number, since it is larger than the sum of its proper divisors (1407983).

81187537 is a wasteful number, since it uses less digits than its factorization.

81187537 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6023.

The product of its digits is 47040, while the sum is 40.

The square root of 81187537 is about 9010.4126986504. The cubic root of 81187537 is about 433.0085336658.

The spelling of 81187537 in words is "eighty-one million, one hundred eighty-seven thousand, five hundred thirty-seven".