81408733531 has 2 divisors, whose sum is σ = 81408733532. Its totient is φ = 81408733530.

The previous prime is 81408733507. The next prime is 81408733559. The reversal of 81408733531 is 13533780418.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81408733531 - 2⁵ = 81408733499 is a prime.

It is a super-2 number, since 2×81408733531² (a number of 23 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (81408733331) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40704366765 + 40704366766.

It is an arithmetic number, because the mean of its divisors is an integer number (40704366766).

Almost surely, 2^81408733531 is an apocalyptic number.

81408733531 is a deficient number, since it is larger than the sum of its proper divisors (1).

81408733531 is an equidigital number, since it uses as much as digits as its factorization.

81408733531 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 241920, while the sum is 43.

The spelling of 81408733531 in words is "eighty-one billion, four hundred eight million, seven hundred thirty-three thousand, five hundred thirty-one".