81631525247 has 2 divisors, whose sum is σ = 81631525248. Its totient is φ = 81631525246.

The previous prime is 81631525237. The next prime is 81631525271. The reversal of 81631525247 is 74252513618.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81631525247 - 2⁴ = 81631525231 is a prime.

It is a super-2 number, since 2×81631525247² (a number of 23 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 81631525198 and 81631525207.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81631525237) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40815762623 + 40815762624.

It is an arithmetic number, because the mean of its divisors is an integer number (40815762624).

Almost surely, 2^81631525247 is an apocalyptic number.

81631525247 is a deficient number, since it is larger than the sum of its proper divisors (1).

81631525247 is an equidigital number, since it uses as much as digits as its factorization.

81631525247 is an evil number, because the sum of its binary digits is even.

The product of its digits is 403200, while the sum is 44.

The spelling of 81631525247 in words is "eighty-one billion, six hundred thirty-one million, five hundred twenty-five thousand, two hundred forty-seven".