81501671 has 2 divisors, whose sum is σ = 81501672. Its totient is φ = 81501670.

The previous prime is 81501643. The next prime is 81501691. The reversal of 81501671 is 17610518.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81501671 - 2¹⁰ = 81500647 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81501691) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40750835 + 40750836.

It is an arithmetic number, because the mean of its divisors is an integer number (40750836).

Almost surely, 2^81501671 is an apocalyptic number.

81501671 is a deficient number, since it is larger than the sum of its proper divisors (1).

81501671 is an equidigital number, since it uses as much as digits as its factorization.

81501671 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1680, while the sum is 29.

The square root of 81501671 is about 9027.8275902899. The cubic root of 81501671 is about 433.5662861201.

The spelling of 81501671 in words is "eighty-one million, five hundred one thousand, six hundred seventy-one".