81887977 has 2 divisors, whose sum is σ = 81887978. Its totient is φ = 81887976.

The previous prime is 81887941. The next prime is 81888007. The reversal of 81887977 is 77978818.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 60902416 + 20985561 = 7804^2 + 4581^2 .

It is a cyclic number.

It is not a de Polignac number, because 81887977 - 2¹⁵ = 81855209 is a prime.

It is not a weakly prime, because it can be changed into another prime (81881977) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40943988 + 40943989.

It is an arithmetic number, because the mean of its divisors is an integer number (40943989).

Almost surely, 2^81887977 is an apocalyptic number.

It is an amenable number.

81887977 is a deficient number, since it is larger than the sum of its proper divisors (1).

81887977 is an equidigital number, since it uses as much as digits as its factorization.

81887977 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1580544, while the sum is 55.

The square root of 81887977 is about 9049.1975887368. The cubic root of 81887977 is about 434.2502202671.

The spelling of 81887977 in words is "eighty-one million, eight hundred eighty-seven thousand, nine hundred seventy-seven".