81553253 has 4 divisors (see below), whose sum is σ = 81894720. Its totient is φ = 81211788.

The previous prime is 81553243. The next prime is 81553259. The reversal of 81553253 is 35235518.

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: 35235518 = 2 ⋅17617759.

It is a cyclic number.

It is not a de Polignac number, because 81553253 - 2⁶ = 81553189 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81553259) 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, 170375 + ... + 170852.

It is an arithmetic number, because the mean of its divisors is an integer number (20473680).

Almost surely, 2^81553253 is an apocalyptic number.

It is an amenable number.

81553253 is a deficient number, since it is larger than the sum of its proper divisors (341467).

81553253 is a wasteful number, since it uses less digits than its factorization.

81553253 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 341466.

The product of its digits is 18000, while the sum is 32.

The square root of 81553253 is about 9030.6839718816. The cubic root of 81553253 is about 433.6577341419.

The spelling of 81553253 in words is "eighty-one million, five hundred fifty-three thousand, two hundred fifty-three".