81662739 has 8 divisors (see below), whose sum is σ = 109448592. Its totient is φ = 54159360.

The previous prime is 81662731. The next prime is 81662767. The reversal of 81662739 is 93726618.

It is a happy number.

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

It is not a de Polignac number, because 81662739 - 2³ = 81662731 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81662739.

It is not an unprimeable number, because it can be changed into a prime (81662731) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 69942 + ... + 71099.

It is an arithmetic number, because the mean of its divisors is an integer number (13681074).

Almost surely, 2^81662739 is an apocalyptic number.

81662739 is a deficient number, since it is larger than the sum of its proper divisors (27785853).

81662739 is a wasteful number, since it uses less digits than its factorization.

81662739 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 141237.

The product of its digits is 108864, while the sum is 42.

The square root of 81662739 is about 9036.7438272865. The cubic root of 81662739 is about 433.8517105421.

The spelling of 81662739 in words is "eighty-one million, six hundred sixty-two thousand, seven hundred thirty-nine".