81885131 has 2 divisors, whose sum is σ = 81885132. Its totient is φ = 81885130.

The previous prime is 81885121. The next prime is 81885137. The reversal of 81885131 is 13158818.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81885131 - 2¹⁴ = 81868747 is a prime.

It is a super-2 number, since 2×81885131² = 13410349357774322, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 81885091 and 81885100.

It is not a weakly prime, because it can be changed into another prime (81885137) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40942565 + 40942566.

It is an arithmetic number, because the mean of its divisors is an integer number (40942566).

Almost surely, 2^81885131 is an apocalyptic number.

81885131 is a deficient number, since it is larger than the sum of its proper divisors (1).

81885131 is an equidigital number, since it uses as much as digits as its factorization.

81885131 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7680, while the sum is 35.

The square root of 81885131 is about 9049.0403358588. The cubic root of 81885131 is about 434.2451894494.

The spelling of 81885131 in words is "eighty-one million, eight hundred eighty-five thousand, one hundred thirty-one".