81560881 has 2 divisors, whose sum is σ = 81560882. Its totient is φ = 81560880.

The previous prime is 81560867. The next prime is 81560887. The reversal of 81560881 is 18806518.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 53523856 + 28037025 = 7316^2 + 5295^2 .

It is a cyclic number.

It is not a de Polignac number, because 81560881 - 2¹¹ = 81558833 is a prime.

It is a super-2 number, since 2×81560881² = 13304354618992322, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 81560881.

It is not a weakly prime, because it can be changed into another prime (81560887) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40780440 + 40780441.

It is an arithmetic number, because the mean of its divisors is an integer number (40780441).

Almost surely, 2^81560881 is an apocalyptic number.

It is an amenable number.

81560881 is a deficient number, since it is larger than the sum of its proper divisors (1).

81560881 is an equidigital number, since it uses as much as digits as its factorization.

81560881 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 15360, while the sum is 37.

The square root of 81560881 is about 9031.1062998948. The cubic root of 81560881 is about 433.6712542978.

The spelling of 81560881 in words is "eighty-one million, five hundred sixty thousand, eight hundred eighty-one".