81907777 has 4 divisors (see below), whose sum is σ = 93608896. Its totient is φ = 70206660.

The previous prime is 81907747. The next prime is 81907781. The reversal of 81907777 is 77770918.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81907777 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81907747) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5850549 + ... + 5850562.

It is an arithmetic number, because the mean of its divisors is an integer number (23402224).

Almost surely, 2^81907777 is an apocalyptic number.

It is an amenable number.

81907777 is a deficient number, since it is larger than the sum of its proper divisors (11701119).

81907777 is a wasteful number, since it uses less digits than its factorization.

81907777 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11701118.

The product of its (nonzero) digits is 172872, while the sum is 46.

The square root of 81907777 is about 9050.2915422654. The cubic root of 81907777 is about 434.2852171078.

The spelling of 81907777 in words is "eighty-one million, nine hundred seven thousand, seven hundred seventy-seven".