81636903497 has 4 divisors (see below), whose sum is σ = 81954557076. Its totient is φ = 81319249920.

The previous prime is 81636903457. The next prime is 81636903499. The reversal of 81636903497 is 79430963618.

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

It can be written as a sum of positive squares in 2 ways, for example, as 45319597456 + 36317306041 = 212884^2 + 190571^2 .

It is a cyclic number.

It is not a de Polignac number, because 81636903497 - 2¹⁴ = 81636887113 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81636903499) 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, 158826404 + ... + 158826917.

It is an arithmetic number, because the mean of its divisors is an integer number (20488639269).

Almost surely, 2^81636903497 is an apocalyptic number.

It is an amenable number.

81636903497 is a deficient number, since it is larger than the sum of its proper divisors (317653579).

81636903497 is a wasteful number, since it uses less digits than its factorization.

81636903497 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 317653578.

The product of its (nonzero) digits is 5878656, while the sum is 56.

The spelling of 81636903497 in words is "eighty-one billion, six hundred thirty-six million, nine hundred three thousand, four hundred ninety-seven".