81704626639 has 2 divisors, whose sum is σ = 81704626640. Its totient is φ = 81704626638.

The previous prime is 81704626631. The next prime is 81704626669. The reversal of 81704626639 is 93662640718.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81704626639 - 2³ = 81704626631 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81704626631) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40852313319 + 40852313320.

It is an arithmetic number, because the mean of its divisors is an integer number (40852313320).

Almost surely, 2^81704626639 is an apocalyptic number.

81704626639 is a deficient number, since it is larger than the sum of its proper divisors (1).

81704626639 is an equidigital number, since it uses as much as digits as its factorization.

81704626639 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2612736, while the sum is 52.

The spelling of 81704626639 in words is "eighty-one billion, seven hundred four million, six hundred twenty-six thousand, six hundred thirty-nine".