81609623 has 2 divisors, whose sum is σ = 81609624. Its totient is φ = 81609622.

The previous prime is 81609613. The next prime is 81609629. The reversal of 81609623 is 32690618.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81609623 - 2¹⁰ = 81608599 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81609629) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40804811 + 40804812.

It is an arithmetic number, because the mean of its divisors is an integer number (40804812).

Almost surely, 2^81609623 is an apocalyptic number.

81609623 is a deficient number, since it is larger than the sum of its proper divisors (1).

81609623 is an equidigital number, since it uses as much as digits as its factorization.

81609623 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 15552, while the sum is 35.

The square root of 81609623 is about 9033.8044588091. The cubic root of 81609623 is about 433.7576265660.

The spelling of 81609623 in words is "eighty-one million, six hundred nine thousand, six hundred twenty-three".