81540031 has 2 divisors, whose sum is σ = 81540032. Its totient is φ = 81540030.

The previous prime is 81539993. The next prime is 81540079. The reversal of 81540031 is 13004518.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81540031 - 2⁷ = 81539903 is a prime.

It is a super-2 number, since 2×81540031² = 13297553310961922, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 81539984 and 81540011.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81540331) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40770015 + 40770016.

It is an arithmetic number, because the mean of its divisors is an integer number (40770016).

Almost surely, 2^81540031 is an apocalyptic number.

81540031 is a deficient number, since it is larger than the sum of its proper divisors (1).

81540031 is an equidigital number, since it uses as much as digits as its factorization.

81540031 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 480, while the sum is 22.

The square root of 81540031 is about 9029.9518824853. The cubic root of 81540031 is about 433.6342969715.

Adding to 81540031 its reverse (13004518), we get a palindrome (94544549).

The spelling of 81540031 in words is "eighty-one million, five hundred forty thousand, thirty-one".