81560639 has 2 divisors, whose sum is σ = 81560640. Its totient is φ = 81560638.

The previous prime is 81560623. The next prime is 81560657. The reversal of 81560639 is 93606518.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81560639 - 2⁴ = 81560623 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81560669) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40780319 + 40780320.

It is an arithmetic number, because the mean of its divisors is an integer number (40780320).

Almost surely, 2^81560639 is an apocalyptic number.

81560639 is a deficient number, since it is larger than the sum of its proper divisors (1).

81560639 is an equidigital number, since it uses as much as digits as its factorization.

81560639 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 38880, while the sum is 38.

The square root of 81560639 is about 9031.0929017478. The cubic root of 81560639 is about 433.6708253807.

The spelling of 81560639 in words is "eighty-one million, five hundred sixty thousand, six hundred thirty-nine".