81629890609 has 2 divisors, whose sum is σ = 81629890610. Its totient is φ = 81629890608.

The previous prime is 81629890579. The next prime is 81629890621. The reversal of 81629890609 is 90609892618.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 81626204209 + 3686400 = 285703^2 + 1920^2 .

It is a cyclic number.

It is not a de Polignac number, because 81629890609 - 2¹³ = 81629882417 is a prime.

It is not a weakly prime, because it can be changed into another prime (81629890679) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40814945304 + 40814945305.

It is an arithmetic number, because the mean of its divisors is an integer number (40814945305).

Almost surely, 2^81629890609 is an apocalyptic number.

It is an amenable number.

81629890609 is a deficient number, since it is larger than the sum of its proper divisors (1).

81629890609 is an equidigital number, since it uses as much as digits as its factorization.

81629890609 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3359232, while the sum is 58.

The spelling of 81629890609 in words is "eighty-one billion, six hundred twenty-nine million, eight hundred ninety thousand, six hundred nine".