81549547 has 2 divisors, whose sum is σ = 81549548. Its totient is φ = 81549546.

The previous prime is 81549491. The next prime is 81549557. The reversal of 81549547 is 74594518.

It is a strong prime.

81549547 is a truncatable prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81549547 is a prime.

It is not a weakly prime, because it can be changed into another prime (81549557) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40774773 + 40774774.

It is an arithmetic number, because the mean of its divisors is an integer number (40774774).

Almost surely, 2^81549547 is an apocalyptic number.

81549547 is a deficient number, since it is larger than the sum of its proper divisors (1).

81549547 is an equidigital number, since it uses as much as digits as its factorization.

81549547 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 201600, while the sum is 43.

The square root of 81549547 is about 9030.4787802198. The cubic root of 81549547 is about 433.6511651830.

The spelling of 81549547 in words is "eighty-one million, five hundred forty-nine thousand, five hundred forty-seven".