81603993 has 8 divisors (see below), whose sum is σ = 114532000. Its totient is φ = 51539328.

The previous prime is 81603979. The next prime is 81604001. The reversal of 81603993 is 39930618.

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

It is not a de Polignac number, because 81603993 - 2⁸ = 81603737 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (81603943) 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, 715768 + ... + 715881.

It is an arithmetic number, because the mean of its divisors is an integer number (14316500).

Almost surely, 2^81603993 is an apocalyptic number.

It is an amenable number.

81603993 is a deficient number, since it is larger than the sum of its proper divisors (32928007).

81603993 is a wasteful number, since it uses less digits than its factorization.

81603993 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1431671.

The product of its (nonzero) digits is 34992, while the sum is 39.

The square root of 81603993 is about 9033.4928460701. The cubic root of 81603993 is about 433.7476517963.

The spelling of 81603993 in words is "eighty-one million, six hundred three thousand, nine hundred ninety-three".