81518977 has 2 divisors, whose sum is σ = 81518978. Its totient is φ = 81518976.

The previous prime is 81518963. The next prime is 81518989. The reversal of 81518977 is 77981518.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 77422401 + 4096576 = 8799^2 + 2024^2 .

It is a cyclic number.

It is not a de Polignac number, because 81518977 - 2⁷ = 81518849 is a prime.

It is a super-2 number, since 2×81518977² = 13290687222253058, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (81518917) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40759488 + 40759489.

It is an arithmetic number, because the mean of its divisors is an integer number (40759489).

Almost surely, 2^81518977 is an apocalyptic number.

It is an amenable number.

81518977 is a deficient number, since it is larger than the sum of its proper divisors (1).

81518977 is an equidigital number, since it uses as much as digits as its factorization.

81518977 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 141120, while the sum is 46.

The square root of 81518977 is about 9028.7860202798. The cubic root of 81518977 is about 433.5969716551.

The spelling of 81518977 in words is "eighty-one million, five hundred eighteen thousand, nine hundred seventy-seven".