81553793 has 4 divisors (see below), whose sum is σ = 81574320. Its totient is φ = 81533268.

The previous prime is 81553783. The next prime is 81553799. The reversal of 81553793 is 39735518.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 39735518 = 2 ⋅19867759.

It is a cyclic number.

It is not a de Polignac number, because 81553793 - 2¹⁶ = 81488257 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81553793.

It is not an unprimeable number, because it can be changed into a prime (81553799) 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, 2183 + ... + 12956.

It is an arithmetic number, because the mean of its divisors is an integer number (20393580).

Almost surely, 2^81553793 is an apocalyptic number.

It is an amenable number.

81553793 is a deficient number, since it is larger than the sum of its proper divisors (20527).

81553793 is a wasteful number, since it uses less digits than its factorization.

81553793 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20526.

The product of its digits is 113400, while the sum is 41.

The square root of 81553793 is about 9030.7138698998. The cubic root of 81553793 is about 433.6586912861.

The spelling of 81553793 in words is "eighty-one million, five hundred fifty-three thousand, seven hundred ninety-three".