81731546 has 16 divisors (see below), whose sum is σ = 139794984. Its totient is φ = 35503104.

The previous prime is 81731539. The next prime is 81731549. The reversal of 81731546 is 64513718.

It can be written as a sum of positive squares in 4 ways, for example, as 51051025 + 30680521 = 7145^2 + 5539^2 .

It is a super-2 number, since 2×81731546² = 13360091223100232, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81731549) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 92015 + ... + 92898.

Almost surely, 2^81731546 is an apocalyptic number.

81731546 is a deficient number, since it is larger than the sum of its proper divisors (58063438).

81731546 is a wasteful number, since it uses less digits than its factorization.

81731546 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 184945.

The product of its digits is 20160, while the sum is 35.

The square root of 81731546 is about 9040.5500938826. The cubic root of 81731546 is about 433.9735272349.

The spelling of 81731546 in words is "eighty-one million, seven hundred thirty-one thousand, five hundred forty-six".