81910487 has 2 divisors, whose sum is σ = 81910488. Its totient is φ = 81910486.

The previous prime is 81910447. The next prime is 81910523. The reversal of 81910487 is 78401918.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81910487 - 2²² = 77716183 is a prime.

It is equal to p_4774484 and since 81910487 and 4774484 have the same sum of digits, it is a Honaker prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81910487.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81910417) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40955243 + 40955244.

It is an arithmetic number, because the mean of its divisors is an integer number (40955244).

Almost surely, 2^81910487 is an apocalyptic number.

81910487 is a deficient number, since it is larger than the sum of its proper divisors (1).

81910487 is an equidigital number, since it uses as much as digits as its factorization.

81910487 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 16128, while the sum is 38.

The square root of 81910487 is about 9050.4412599608. The cubic root of 81910487 is about 434.2900066406.

The spelling of 81910487 in words is "eighty-one million, nine hundred ten thousand, four hundred eighty-seven".