81499561 has 8 divisors (see below), whose sum is σ = 95747904. Its totient is φ = 68391120.

The previous prime is 81499559. The next prime is 81499571. The reversal of 81499561 is 16599418.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81499561 - 2¹ = 81499559 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81499571) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 284821 + ... + 285106.

It is an arithmetic number, because the mean of its divisors is an integer number (11968488).

Almost surely, 2^81499561 is an apocalyptic number.

It is an amenable number.

81499561 is a deficient number, since it is larger than the sum of its proper divisors (14248343).

81499561 is a wasteful number, since it uses less digits than its factorization.

81499561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 569951.

The product of its digits is 77760, while the sum is 43.

The square root of 81499561 is about 9027.7107286399. The cubic root of 81499561 is about 433.5625445496.

The spelling of 81499561 in words is "eighty-one million, four hundred ninety-nine thousand, five hundred sixty-one".