81707489251 has 2 divisors, whose sum is σ = 81707489252. Its totient is φ = 81707489250.

The previous prime is 81707489219. The next prime is 81707489371. The reversal of 81707489251 is 15298470718.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81707489251 - 2⁵ = 81707489219 is a prime.

It is a super-2 number, since 2×81707489251² (a number of 23 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (81707486251) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40853744625 + 40853744626.

It is an arithmetic number, because the mean of its divisors is an integer number (40853744626).

Almost surely, 2^81707489251 is an apocalyptic number.

81707489251 is a deficient number, since it is larger than the sum of its proper divisors (1).

81707489251 is an equidigital number, since it uses as much as digits as its factorization.

81707489251 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1128960, while the sum is 52.

The spelling of 81707489251 in words is "eighty-one billion, seven hundred seven million, four hundred eighty-nine thousand, two hundred fifty-one".