1381581 has 6 divisors (see below), whose sum is σ = 1995630. Its totient is φ = 921048.

The previous prime is 1381559. The next prime is 1381609. The reversal of 1381581 is 1851831.

1381581 is a `hidden beast` number, since 1 + 3 + 81 + 581 = 666.

It can be written as a sum of positive squares in only one way, i.e., 1121481 + 260100 = 1059^2 + 510^2 .

It is not a de Polignac number, because 1381581 - 2⁶ = 1381517 is a prime.

It is a super-2 number, since 2×1381581² = 3817532119122, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1381381) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 76746 + ... + 76763.

It is an arithmetic number, because the mean of its divisors is an integer number (332605).

2^1381581 is an apocalyptic number.

It is an amenable number.

1381581 is a deficient number, since it is larger than the sum of its proper divisors (614049).

1381581 is a wasteful number, since it uses less digits than its factorization.

1381581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 153515 (or 153512 counting only the distinct ones).

The product of its digits is 960, while the sum is 27.

The square root of 1381581 is about 1175.4067381124. The cubic root of 1381581 is about 111.3761284637.

The spelling of 1381581 in words is "one million, three hundred eighty-one thousand, five hundred eighty-one".