81555311 has 2 divisors, whose sum is σ = 81555312. Its totient is φ = 81555310.

The previous prime is 81555283. The next prime is 81555317. The reversal of 81555311 is 11355518.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81555311 - 2¹⁴ = 81538927 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81555317) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40777655 + 40777656.

It is an arithmetic number, because the mean of its divisors is an integer number (40777656).

Almost surely, 2^81555311 is an apocalyptic number.

81555311 is a deficient number, since it is larger than the sum of its proper divisors (1).

81555311 is an equidigital number, since it uses as much as digits as its factorization.

81555311 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3000, while the sum is 29.

The square root of 81555311 is about 9030.7979160205. The cubic root of 81555311 is about 433.6613819020.

The spelling of 81555311 in words is "eighty-one million, five hundred fifty-five thousand, three hundred eleven".