81475640 has 16 divisors (see below), whose sum is σ = 183320280. Its totient is φ = 32590240.

The previous prime is 81475633. The next prime is 81475643. The reversal of 81475640 is 4657418.

It is a super-3 number, since 3×81475640³ (a number of 25 digits) contains 333 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 81475640.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81475643) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1018406 + ... + 1018485.

Almost surely, 2^81475640 is an apocalyptic number.

It is an amenable number.

81475640 is an abundant number, since it is smaller than the sum of its proper divisors (101844640).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81475640 is a wasteful number, since it uses less digits than its factorization.

81475640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2036902 (or 2036898 counting only the distinct ones).

The product of its (nonzero) digits is 26880, while the sum is 35.

The square root of 81475640 is about 9026.3857661857. The cubic root of 81475640 is about 433.5201219714.

The spelling of 81475640 in words is "eighty-one million, four hundred seventy-five thousand, six hundred forty".