81039977 has 2 divisors, whose sum is σ = 81039978. Its totient is φ = 81039976.

The previous prime is 81039913. The next prime is 81039979. The reversal of 81039977 is 77993018.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 69622336 + 11417641 = 8344^2 + 3379^2 .

It is a cyclic number.

It is not a de Polignac number, because 81039977 - 2⁶ = 81039913 is a prime.

Together with 81039979, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (81039979) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40519988 + 40519989.

It is an arithmetic number, because the mean of its divisors is an integer number (40519989).

Almost surely, 2^81039977 is an apocalyptic number.

It is an amenable number.

81039977 is a deficient number, since it is larger than the sum of its proper divisors (1).

81039977 is an equidigital number, since it uses as much as digits as its factorization.

81039977 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 95256, while the sum is 44.

The square root of 81039977 is about 9002.2206704790. The cubic root of 81039977 is about 432.7460406333.

The spelling of 81039977 in words is "eighty-one million, thirty-nine thousand, nine hundred seventy-seven".