81781142 has 16 divisors (see below), whose sum is σ = 126669312. Its totient is φ = 39574080.

The previous prime is 81781109. The next prime is 81781153. The reversal of 81781142 is 24118718.

It is a junction number, because it is equal to n+sod(n) for n = 81781099 and 81781108.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6488 + ... + 14340.

It is an arithmetic number, because the mean of its divisors is an integer number (7916832).

Almost surely, 2^81781142 is an apocalyptic number.

81781142 is a gapful number since it is divisible by the number (82) formed by its first and last digit.

81781142 is a deficient number, since it is larger than the sum of its proper divisors (44888170).

81781142 is a wasteful number, since it uses less digits than its factorization.

81781142 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8023.

The product of its digits is 3584, while the sum is 32.

The square root of 81781142 is about 9043.2926525685. The cubic root of 81781142 is about 434.0612901612.

The spelling of 81781142 in words is "eighty-one million, seven hundred eighty-one thousand, one hundred forty-two".