81637743 has 8 divisors (see below), whose sum is σ = 118745856. Its totient is φ = 49477400.

The previous prime is 81637739. The next prime is 81637753. The reversal of 81637743 is 34773618.

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

It is a cyclic number.

It is not a de Polignac number, because 81637743 - 2² = 81637739 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81637753) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1236903 + ... + 1236968.

It is an arithmetic number, because the mean of its divisors is an integer number (14843232).

Almost surely, 2^81637743 is an apocalyptic number.

81637743 is a deficient number, since it is larger than the sum of its proper divisors (37108113).

81637743 is a wasteful number, since it uses less digits than its factorization.

81637743 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2473885.

The product of its digits is 84672, while the sum is 39.

The square root of 81637743 is about 9035.3607011563. The cubic root of 81637743 is about 433.8074403966.

The spelling of 81637743 in words is "eighty-one million, six hundred thirty-seven thousand, seven hundred forty-three".