81157523 has 2 divisors, whose sum is σ = 81157524. Its totient is φ = 81157522.

The previous prime is 81157487. The next prime is 81157529. The reversal of 81157523 is 32575118.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81157523 - 2¹⁰ = 81156499 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81157523.

It is not a weakly prime, because it can be changed into another prime (81157529) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40578761 + 40578762.

It is an arithmetic number, because the mean of its divisors is an integer number (40578762).

Almost surely, 2^81157523 is an apocalyptic number.

81157523 is a deficient number, since it is larger than the sum of its proper divisors (1).

81157523 is an equidigital number, since it uses as much as digits as its factorization.

81157523 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 8400, while the sum is 32.

The square root of 81157523 is about 9008.7470271953. The cubic root of 81157523 is about 432.9551678395.

The spelling of 81157523 in words is "eighty-one million, one hundred fifty-seven thousand, five hundred twenty-three".