81630291031 has 2 divisors, whose sum is σ = 81630291032. Its totient is φ = 81630291030.

The previous prime is 81630290939. The next prime is 81630291103. The reversal of 81630291031 is 13019203618.

Together with next prime (81630291103) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81630291031 - 2⁹ = 81630290519 is a prime.

It is a super-2 number, since 2×81630291031² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81630291131) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40815145515 + 40815145516.

It is an arithmetic number, because the mean of its divisors is an integer number (40815145516).

Almost surely, 2^81630291031 is an apocalyptic number.

81630291031 is a deficient number, since it is larger than the sum of its proper divisors (1).

81630291031 is an equidigital number, since it uses as much as digits as its factorization.

81630291031 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7776, while the sum is 34.

Adding to 81630291031 its reverse (13019203618), we get a palindrome (94649494649).

The spelling of 81630291031 in words is "eighty-one billion, six hundred thirty million, two hundred ninety-one thousand, thirty-one".