81549457 has 16 divisors (see below), whose sum is σ = 92778048. Its totient is φ = 71023680.

The previous prime is 81549449. The next prime is 81549473. The reversal of 81549457 is 75494518.

It is a cyclic number.

It is not a de Polignac number, because 81549457 - 2³ = 81549449 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (43).

Its product of digits (201600) is a multiple of the sum of its prime divisors (3360).

It is not an unprimeable number, because it can be changed into a prime (81549427) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 23443 + ... + 26695.

It is an arithmetic number, because the mean of its divisors is an integer number (5798628).

Almost surely, 2^81549457 is an apocalyptic number.

It is an amenable number.

81549457 is a deficient number, since it is larger than the sum of its proper divisors (11228591).

81549457 is a wasteful number, since it uses less digits than its factorization.

81549457 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3360.

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

The square root of 81549457 is about 9030.4737970939. The cubic root of 81549457 is about 433.6510056537.

The spelling of 81549457 in words is "eighty-one million, five hundred forty-nine thousand, four hundred fifty-seven".