81648405 has 30 divisors (see below), whose sum is σ = 146689026. Its totient is φ = 43448832.

The previous prime is 81648403. The next prime is 81648419. The reversal of 81648405 is 50484618.

81648405 is a `hidden beast` number, since 8 + 1 + 648 + 4 + 0 + 5 = 666.

It can be written as a sum of positive squares in 3 ways, for example, as 14424804 + 67223601 = 3798^2 + 8199^2 .

It is not a de Polignac number, because 81648405 - 2¹ = 81648403 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81648405.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81648401) by changing a digit.

It is a polite number, since it can be written in 29 ways as a sum of consecutive naturals, for example, 181621 + ... + 182069.

Almost surely, 2^81648405 is an apocalyptic number.

It is an amenable number.

81648405 is a deficient number, since it is larger than the sum of its proper divisors (65040621).

81648405 is an frugal number, since it uses more digits than its factorization.

81648405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 915 (or 457 counting only the distinct ones).

The product of its (nonzero) digits is 30720, while the sum is 36.

The square root of 81648405 is about 9035.9506970767. The cubic root of 81648405 is about 433.8263248546.

The spelling of 81648405 in words is "eighty-one million, six hundred forty-eight thousand, four hundred five".