81542553 has 4 divisors (see below), whose sum is σ = 108723408. Its totient is φ = 54361700.

The previous prime is 81542507. The next prime is 81542581. The reversal of 81542553 is 35524518.

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.

It is a cyclic number.

It is not a de Polignac number, because 81542553 - 2⁸ = 81542297 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (81542753) 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, 13590423 + ... + 13590428.

It is an arithmetic number, because the mean of its divisors is an integer number (27180852).

Almost surely, 2^81542553 is an apocalyptic number.

It is an amenable number.

81542553 is a deficient number, since it is larger than the sum of its proper divisors (27180855).

81542553 is a wasteful number, since it uses less digits than its factorization.

81542553 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27180854.

The product of its digits is 24000, while the sum is 33.

The square root of 81542553 is about 9030.0915277753. The cubic root of 81542553 is about 433.6387676363.

The spelling of 81542553 in words is "eighty-one million, five hundred forty-two thousand, five hundred fifty-three".