81487705 has 16 divisors (see below), whose sum is σ = 107879184. Its totient is φ = 58705920.

The previous prime is 81487697. The next prime is 81487711. The reversal of 81487705 is 50778418.

It can be written as a sum of positive squares in 8 ways, for example, as 27846729 + 53640976 = 5277^2 + 7324^2 .

It is not a de Polignac number, because 81487705 - 2³ = 81487697 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 12624 + ... + 17953.

It is an arithmetic number, because the mean of its divisors is an integer number (6742449).

Almost surely, 2^81487705 is an apocalyptic number.

It is an amenable number.

81487705 is a deficient number, since it is larger than the sum of its proper divisors (26391479).

81487705 is a wasteful number, since it uses less digits than its factorization.

81487705 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30636.

The product of its (nonzero) digits is 62720, while the sum is 40.

The square root of 81487705 is about 9027.0540598802. The cubic root of 81487705 is about 433.5415196232.

The spelling of 81487705 in words is "eighty-one million, four hundred eighty-seven thousand, seven hundred five".