81535931 has 2 divisors, whose sum is σ = 81535932. Its totient is φ = 81535930.

The previous prime is 81535879. The next prime is 81535939. The reversal of 81535931 is 13953518.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81535931 is a prime.

It is a super-2 number, since 2×81535931² = 13296216088073522, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 81535891 and 81535900.

It is not a weakly prime, because it can be changed into another prime (81535939) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40767965 + 40767966.

It is an arithmetic number, because the mean of its divisors is an integer number (40767966).

Almost surely, 2^81535931 is an apocalyptic number.

81535931 is a deficient number, since it is larger than the sum of its proper divisors (1).

81535931 is an equidigital number, since it uses as much as digits as its factorization.

81535931 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 16200, while the sum is 35.

The square root of 81535931 is about 9029.7248573808. The cubic root of 81535931 is about 433.6270288424.

The spelling of 81535931 in words is "eighty-one million, five hundred thirty-five thousand, nine hundred thirty-one".