81006503 has 4 divisors (see below), whose sum is σ = 83619648. Its totient is φ = 78393360.

The previous prime is 81006491. The next prime is 81006577. The reversal of 81006503 is 30560018.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81006503 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81006103) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1306526 + ... + 1306587.

It is an arithmetic number, because the mean of its divisors is an integer number (20904912).

Almost surely, 2^81006503 is an apocalyptic number.

81006503 is a deficient number, since it is larger than the sum of its proper divisors (2613145).

81006503 is a wasteful number, since it uses less digits than its factorization.

81006503 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2613144.

The product of its (nonzero) digits is 720, while the sum is 23.

The square root of 81006503 is about 9000.3612705269. The cubic root of 81006503 is about 432.6864497317.

The spelling of 81006503 in words is "eighty-one million, six thousand, five hundred three".