81473640 has 64 divisors (see below), whose sum is σ = 245851200. Its totient is φ = 21599232.

The previous prime is 81473629. The next prime is 81473657. The reversal of 81473640 is 4637418.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 19584 + ... + 23376.

It is an arithmetic number, because the mean of its divisors is an integer number (3841425).

Almost surely, 2^81473640 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81473640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (122925600).

81473640 is an abundant number, since it is smaller than the sum of its proper divisors (164377560).

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

81473640 is a wasteful number, since it uses less digits than its factorization.

81473640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3986 (or 3982 counting only the distinct ones).

The product of its (nonzero) digits is 16128, while the sum is 33.

The square root of 81473640 is about 9026.2749791927. The cubic root of 81473640 is about 433.5165747053.

The spelling of 81473640 in words is "eighty-one million, four hundred seventy-three thousand, six hundred forty".