81549401 has 2 divisors, whose sum is σ = 81549402. Its totient is φ = 81549400.

The previous prime is 81549397. The next prime is 81549427. The reversal of 81549401 is 10494518.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 40896025 + 40653376 = 6395^2 + 6376^2 .

It is a cyclic number.

It is not a de Polignac number, because 81549401 - 2² = 81549397 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (81549491) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40774700 + 40774701.

It is an arithmetic number, because the mean of its divisors is an integer number (40774701).

Almost surely, 2^81549401 is an apocalyptic number.

It is an amenable number.

81549401 is a deficient number, since it is larger than the sum of its proper divisors (1).

81549401 is an equidigital number, since it uses as much as digits as its factorization.

81549401 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5760, while the sum is 32.

The square root of 81549401 is about 9030.4706964809. The cubic root of 81549401 is about 433.6509063910.

The spelling of 81549401 in words is "eighty-one million, five hundred forty-nine thousand, four hundred one".