1538640 has 60 divisors (see below), whose sum is σ = 5169684. Its totient is φ = 410112.

The previous prime is 1538633. The next prime is 1538657. The reversal of 1538640 is 468351.

1538640 is a `hidden beast` number, since 15 + 3 + 8 + 640 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 266256 + 1272384 = 516^2 + 1128^2 .

It is a tau number, because it is divible by the number of its divisors (60).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 349 + ... + 1788.

2^1538640 is an apocalyptic number.

1538640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1538640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2584842).

1538640 is an abundant number, since it is smaller than the sum of its proper divisors (3631044).

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

1538640 is a wasteful number, since it uses less digits than its factorization.

1538640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2156 (or 2147 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 27.

The square root of 1538640 is about 1240.4192839520. The cubic root of 1538640 is about 115.4460308944.

The spelling of 1538640 in words is "one million, five hundred thirty-eight thousand, six hundred forty".