81211787 has 2 divisors, whose sum is σ = 81211788. Its totient is φ = 81211786.

The previous prime is 81211759. The next prime is 81211799. The reversal of 81211787 is 78711218.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81211787 - 2¹⁰ = 81210763 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (81211087) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40605893 + 40605894.

It is an arithmetic number, because the mean of its divisors is an integer number (40605894).

Almost surely, 2^81211787 is an apocalyptic number.

81211787 is a deficient number, since it is larger than the sum of its proper divisors (1).

81211787 is an equidigital number, since it uses as much as digits as its factorization.

81211787 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6272, while the sum is 35.

The square root of 81211787 is about 9011.7582635133. The cubic root of 81211787 is about 433.0516413152.

The spelling of 81211787 in words is "eighty-one million, two hundred eleven thousand, seven hundred eighty-seven".