81642787 has 8 divisors (see below), whose sum is σ = 82967040. Its totient is φ = 80325960.

The previous prime is 81642773. The next prime is 81642797. The reversal of 81642787 is 78724618.

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-81642787 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81642707) 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, 22908 + ... + 26230.

It is an arithmetic number, because the mean of its divisors is an integer number (10370880).

Almost surely, 2^81642787 is an apocalyptic number.

81642787 is a deficient number, since it is larger than the sum of its proper divisors (1324253).

81642787 is a wasteful number, since it uses less digits than its factorization.

81642787 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3713.

The product of its digits is 150528, while the sum is 43.

The square root of 81642787 is about 9035.6398223922. The cubic root of 81642787 is about 433.8163744982.

The spelling of 81642787 in words is "eighty-one million, six hundred forty-two thousand, seven hundred eighty-seven".