81556697 has 2 divisors, whose sum is σ = 81556698. Its totient is φ = 81556696.

The previous prime is 81556693. The next prime is 81556723. The reversal of 81556697 is 79665518.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 81522841 + 33856 = 9029^2 + 184^2 .

It is a cyclic number.

It is not a de Polignac number, because 81556697 - 2² = 81556693 is a prime.

It is not a weakly prime, because it can be changed into another prime (81556693) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40778348 + 40778349.

It is an arithmetic number, because the mean of its divisors is an integer number (40778349).

Almost surely, 2^81556697 is an apocalyptic number.

It is an amenable number.

81556697 is a deficient number, since it is larger than the sum of its proper divisors (1).

81556697 is an equidigital number, since it uses as much as digits as its factorization.

81556697 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 453600, while the sum is 47.

The square root of 81556697 is about 9030.8746530998. The cubic root of 81556697 is about 433.6638385222.

The spelling of 81556697 in words is "eighty-one million, five hundred fifty-six thousand, six hundred ninety-seven".