81491483477 has 2 divisors, whose sum is σ = 81491483478. Its totient is φ = 81491483476.

The previous prime is 81491483473. The next prime is 81491483503. The reversal of 81491483477 is 77438419418.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 64496189521 + 16995293956 = 253961^2 + 130366^2 .

It is a cyclic number.

It is not a de Polignac number, because 81491483477 - 2² = 81491483473 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81491483473) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40745741738 + 40745741739.

It is an arithmetic number, because the mean of its divisors is an integer number (40745741739).

Almost surely, 2^81491483477 is an apocalyptic number.

It is an amenable number.

81491483477 is a deficient number, since it is larger than the sum of its proper divisors (1).

81491483477 is an equidigital number, since it uses as much as digits as its factorization.

81491483477 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5419008, while the sum is 56.

The spelling of 81491483477 in words is "eighty-one billion, four hundred ninety-one million, four hundred eighty-three thousand, four hundred seventy-seven".